RESUMO
Vriesea bahiana, Hohenbergia castellanosii and Encholirium spectabile are endemic Brazilian species that are considered endemic or endangered. Development of strategies to conserve these species is important to prevent irreversible genetic erosion. The objective of this study was to evaluate the post-seminal development and seed cryopreservation of three endemic or in danger of extinction bromeliad species in Brazil, to obtain a protocol that can safeguard the genetic variability of these species. In the seed cryopreservation assay, we evaluated five desiccation periods. The seeds in the cryotubes were taken from the desiccator and immediately plunged into liquid nitrogen. For the analysis of post-seminal development, seeds in different germination stages were collected and evaluated by light and scanning electron microscopy. Vriesea bahiana seeds frozen in liquid nitrogen presented almost 100% germination, indicating dormancy break of this species. Vriesea bahiana can be cryopreserved with 5.9% water content after being dried for 24 hours. Hohenbergia castellanosii and E. spectabile seeds did not need to be desiccated before being cryopreserved. The most relevant morphological traits for differentiation of genera and subfamilies of Bromeliaceae are the shape and type of seed appendages. In this study, all three species presented well-differentiated size and shape of their structures.
Assuntos
Dessecação , Germinação , Brasil , Criopreservação , SementesRESUMO
The main drivers of diversification of freshwater fishes in Cuba are not yet well understood. For example, salt tolerance was thought as the main factor involved in the diversification of Gambusia punctata species group in this archipelago. However, evidence from a recent DNA barcoding survey suggested the presence of cryptic species and no correlation between species delimitation and level of salinity. In this study, we analyzed the cryptic diversification of G. punctata species group in Cuba, based on a comprehensive sampling of its distribution and including habitats with different salinity levels. We evaluated the patterns of molecular divergence of the samples by sequencing a set of mitochondrial DNA (mtDNA) regions and genotyping nine nuclear microsatellite loci. We also used cytochrome b gene (cytb) partial sequences and these microsatellite loci to analyze population structure inside putative species. Five mtDNA well-differentiated haplogroups were found, four of them also identified by the analysis of the microsatellite polymorphism which corresponds to two already recognized species, G. punctata, and G. rhizophorae, and three putative new species. The extent of hybrid zones between these groups is also described. In each group, populations inhabiting environments with contrasting salinity levels were identified, indicating a generalized trait not specific to G. rhizophorae. The geographic distribution of the groups suggested a strong association with major relict territories of the Cuban Archipelago that was periodically joined or split-up by changes in seawater levels and land uplifts. Salinity tolerance might have facilitated sporadic and long-distance oversea dispersal but did not prevent speciation in the Cuban archipelago.
Assuntos
Ciprinodontiformes/classificação , Ciprinodontiformes/genética , Ecossistema , Variação Genética , Animais , Cuba , Citocromos b/genética , DNA Mitocondrial/análise , DNA Mitocondrial/genética , Especiação Genética , Geologia , Repetições de Microssatélites/genética , Filogenia , Filogeografia , Água do Mar , Análise de Sequência de DNARESUMO
Given that the role of C-type natriuretic peptide (CNP) in the regulation of vascular tone in hypertensive states is unclear, we hypothesized that impaired response of the nitric oxide system to CNP in spontaneously hypertensive rats (SHR) could affect vascular relaxation induced by the peptide in this model of hypertension, and that other endothelial systems or potassium channels opening could also be involved. We examined the effect of CNP on isolated SHR aortas, and the hindlimb vascular resistance (HVR) in response to CNP administration compared to normotensive rats. Aortas were mounted in an isometric organ bath and contracted with phenylephrine. CNP relaxed arteries in a concentration-dependent manner but was less potent in inducing relaxation in SHR. The action of CNP was diminished by removal of the endothelium, inhibition of nitric oxide synthase by Nω-nitro-L-arginine methyl ester, and inhibition of soluble guanylyl cyclase by 1H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one in both groups. In contrast, blockade of cyclooxygenase or subtype 2 bradykinin receptor increased CNP potency only in SHR. In both Wistar and SHR, CNP relaxation was blunted by tetraethylammonium and partially inhibited by BaCl2 and iberiotoxin, indicating that it was due to opening of the Kir and BKCa channels. However, SHR seem to be more sensitive to Kir channel blockade and less sensitive to BKCa channel blockade than normotensive rats. In addition, CNP decreases HVR in Wistar and SHR, but the effect of CNP increasing blood flow was more marked in SHR. We conclude that CNP induces aorta relaxation by activation of the nitric oxide system and opening of potassium channels, but the response to the peptide is impaired in conductance vessel of hypertensive rats.
Assuntos
Endotélio Vascular/fisiologia , Peptídeo Natriurético Tipo C/fisiologia , Animais , Masculino , Ratos , Ratos Endogâmicos SHR , Ratos Wistar , Resistência VascularRESUMO
OBJECTIVE: The aim of this study was to investigate the effects of chronic treatment with atrial natriuretic peptide (ANP) on renal function, nitric oxide (NO) system, oxidative stress, collagen content and apoptosis in kidneys of spontaneously hypertensive rats (SHR), as well as sex-related differences in the response to the treatment. METHODS: 10 week-old male and female SHR were infused with ANP (100 ng/h/rat) or saline (NaCl 0.9%) for 14 days (subcutaneous osmotic pumps). Systolic blood pressure (SBP) was recorded and diuresis and natriuresis were determined. After treatment, renal NO synthase (NOS) activity and eNOS expression were evaluated. Thiobarbituric acid-reactive substances (TBARS), glutathione concentration and glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were determined in the kidney. Collagen was identified in renal slices by Sirius red staining and apoptosis by Tunel assay. RESULTS: Female SHR showed lower SBP, oxidative stress, collagen content and apoptosis in kidney, and higher renal NOS activity and eNOS protein content, than males. ANP lowered SBP, increased diuresis, natriuresis, renal NOS activity and eNOS expression in both sexes. Renal response to ANP was more marked in females than in males. In kidney, ANP reduced TBARS, renal collagen content and apoptosis, and increased glutathione concentration and activity of GPx and SOD enzymes in both sexes. CONCLUSIONS: Female SHR exhibited less organ damage than males. Chronic ANP treatment would ameliorate hypertension and end-organ damage in the kidney by reducing oxidative stress, increasing NO-system activity, and diminishing collagen content and apoptosis, in both sexes.
Assuntos
Fator Natriurético Atrial/farmacologia , Hipertensão/metabolismo , Hipertensão/fisiopatologia , Ratos Endogâmicos SHR , Animais , Apoptose/efeitos dos fármacos , Fator Natriurético Atrial/administração & dosagem , Pressão Sanguínea/efeitos dos fármacos , Diurese/efeitos dos fármacos , Feminino , Hipertensão/tratamento farmacológico , Hipertensão/etiologia , Rim/anatomia & histologia , Rim/efeitos dos fármacos , Rim/metabolismo , Rim/patologia , Masculino , Natriurese/efeitos dos fármacos , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Ratos , Fatores SexuaisRESUMO
The aim of this study was to evaluate whether L-Arginine (L-Arg) supplementation modifies nitric oxide (NO) system and consequently aquaporin-2 (AQP2) expression in the renal outer medulla of streptozotocin-diabetic rats at an early time point after induction of diabetes. Male Wistar rats were divided in four groups: Control, Diabetic, Diabetic treated with L-Arginine and Control treated with L-Arginine. Nitric oxide synthase (NOS) activity was estimated by [14C] L-citrulline production in homogenates of the renal outer medulla and by NADPH-diaphorase staining in renal outer medullary tubules. Western blot was used to detect the expression of AQP2 and NOS types I and III; real time PCR was used to quantify AQP2 mRNA. The expression of both NOS isoforms, NOS I and NOS III, was decreased in the renal outer medulla of diabetic rats and L-Arg failed to prevent these decreases. However, L-Arg improved NO production, NADPH-diaphorase activity in collecting ducts and other tubular structures, and NOS activity in renal homogenates from diabetic rats. AQP2 protein and mRNA were decreased in the renal outer medulla of diabetic rats and L-Arg administration prevented these decreases. These results suggest that the decreased NOS activity in collecting ducts of the renal outer medulla may cause, at least in part, the decreased expression of AQP2 in this model of diabetes and constitute additional evidence supporting a role for NO in contributing to renal water reabsorption through the modulation of AQP2 expression in this pathological condition. However, we cannot discard that another pathway different from NOS also exists that links L-Arg to AQP2 expression.
Assuntos
Aquaporina 2/biossíntese , Arginina/farmacologia , Diabetes Mellitus Experimental/patologia , Óxido Nítrico Sintase Tipo III/metabolismo , Óxido Nítrico Sintase Tipo I/metabolismo , Animais , Aquaporina 2/metabolismo , Glicemia/efeitos dos fármacos , Citrulina/biossíntese , Diabetes Mellitus Experimental/induzido quimicamente , Medula Renal/patologia , Túbulos Renais Coletores/patologia , Masculino , NADPH Desidrogenase/metabolismo , Óxido Nítrico/metabolismo , Ratos , Ratos Wistar , EstreptozocinaRESUMO
INTRODUCTION: The aim of this study was to investigate both the effects of chronic treatment with atrial natriuretic peptide (ANP) on systolic blood pressure (SBP), cardiac nitric oxide (NO) system, oxidative stress, hypertrophy, fibrosis and apoptosis in spontaneously hypertensive rats (SHR), and sex-related differences in the response to the treatment. METHODS: 10 week-old male and female SHR were infused with ANP (100 ng/hr/rat) or saline (NaCl 0.9%) for 14 days (subcutaneous osmotic pumps). SBP was recorded and nitrites and nitrates excretion (NOx) were determined. After treatment, NO synthase (NOS) activity, eNOS expression, thiobarbituric acid-reactive substances (TBARS) and glutathione concentration were determined in left ventricle, as well as the activity of glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD). Morphological studies in left ventricle were performed in slices stained with hematoxylin-eosin or Sirius red to identify collagen as a fibrosis indicator; immunohistochemistry was employed for identification of transforming growth factor beta; and apoptosis was evaluated by Tunel assay. RESULTS: Female SHR showed lower SBP, higher NO-system activity and less oxidative stress, fibrosis and hypertrophy in left ventricle, as well as higher cardiac NOS activity, eNOS protein content and NOx excretion than male SHR. Although ANP treatment lowered blood pressure and increased NOS activity and eNOS expression in both sexes, cardiac NOS response to ANP was more marked in females. In left ventricle, ANP reduced TBARS and increased glutathione concentration and activity of CAT and SOD enzymes in both sexes, as well as GPx activity in males. ANP decreased fibrosis and apoptosis in hearts from male and female SHR but females showed less end-organ damage in heart. Chronic ANP treatment would ameliorate hypertension and end-organ damage in heart by reducing oxidative stress, increasing NO-system activity, and diminishing fibrosis and hypertrophy.
Assuntos
Anti-Hipertensivos/farmacologia , Fator Natriurético Atrial/farmacologia , Hipertensão/fisiopatologia , Animais , Anti-Hipertensivos/administração & dosagem , Apoptose/efeitos dos fármacos , Fator Natriurético Atrial/administração & dosagem , Pressão Sanguínea/efeitos dos fármacos , Catalase/metabolismo , Modelos Animais de Doenças , Feminino , Glutationa/metabolismo , Coração/efeitos dos fármacos , Coração/fisiopatologia , Hipertensão/tratamento farmacológico , Hipertensão/etiologia , Masculino , Miocárdio/metabolismo , Miocárdio/patologia , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Estresse Oxidativo , Ratos Endogâmicos SHR , Fatores Sexuais , Superóxido Dismutase/metabolismo , Fator de Crescimento Transformador beta/metabolismoRESUMO
Epidemiological and intervention studies have shown that the intake of certain chocolates or cocoa products decreases blood pressure (BP) in humans. (-)-Epicatechin is the most abundant flavanol present in cocoa seeds and its derived foods. This work investigates the effects of dietary (-)-epicatechin on BP in rats that received N(ω)-nitro-l-arginine methyl ester (L-NAME) for 4 days. (-)-Epicatechin administration prevented the 42mm Hg increase in BP associated with the inhibition of NO production in a dose-dependent manner (0.2-4.0g/kg diet). This BP effect was associated with a reduction in L-NAME-mediated increase in the indexes of oxidative stress (plasma TBARS and GSSG/GSH(2) ratio) and with a restoration of the NO concentration. At the vascular level, none of the treatments modified NOS expression, but (-)-epicatechin administration avoided the L-NAME-mediated decrease in eNOS activity and increase in both superoxide anion production and NOX subunit p47(phox) expression. In summary, (-)-epicatechin was able to prevent the increase in BP and in oxidative stress and restored NO bioavailability. The fact that (-)-epicatechin is present in several plants usually consumed by humans gives the possibility of developing diets rich in those plants or pharmacological strategies using that flavonoid to diminish BP in hypertensive subjects.
Assuntos
Pressão Sanguínea/efeitos dos fármacos , Catequina/farmacologia , Hipertensão/tratamento farmacológico , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico/metabolismo , Animais , Pressão Sanguínea/fisiologia , Suplementos Nutricionais , Glutationa/sangue , Dissulfeto de Glutationa/sangue , Masculino , Óxido Nítrico Sintase/biossíntese , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Vasodilatação/efeitos dos fármacosRESUMO
Atrial natriuretic peptide (ANP) is an important regulator of blood pressure (BP). One of the mechanisms whereby ANP impacts BP is by stimulation of nitric oxide (NO) production in different tissues involved in BP control. We hypothesized that ANP-stimulated NO is impaired in the kidneys of spontaneously hypertensive rats (SHR) and this contributes to the development and/or maintenance of high levels of BP. We investigated the effects of ANP on the NO system in SHR, studying the changes in renal nitric oxide synthase (NOS) activity and expression in response to peptide infusion, the signaling pathways implicated in the signaling cascade that activates NOS, and identifying the natriuretic peptide receptors (NPR), guanylyl cyclase receptors (NPR-A and NPR-B) and/or NPR-C, and NOS isoforms involved. In vivo, SHR and Wistar-Kyoto rats (WKY) were infused with saline (0.05 ml/min) or ANP (0.2 µg·kg(-1)·min(-1)). NOS activity and endothelial (eNOS), neuronal (nNOS), and inducible (iNOS) NOS expression were measured in the renal cortex and medulla. In vitro, ANP-induced renal NOS activity was determined in the presence of iNOS and nNOS inhibitors, NPR-A/B blockers, guanine nucleotide-regulatory (G(i)) protein, and calmodulin inhibitors. Renal NOS activity was higher in SHR than in WKY. ANP increased NOS activity, but activation was lower in SHR than in WKY. ANP had no effect on expression of NOS isoforms. ANP-induced NOS activity was not modified by iNOS and nNOS inhibitors. NPR-A/B blockade blunted NOS stimulation via ANP in kidney. The renal NOS response to ANP was reduced by G(i) protein and calmodulin inhibitors. We conclude that ANP interacts with NPR-C, activating Ca-calmodulin eNOS through G(i) protein. NOS activation also involves NPR-A/B. The NOS response to ANP was diminished in kidneys of SHR. The impaired NO system response to ANP in SHR participates in the maintenance of high blood pressure.
Assuntos
Fator Natriurético Atrial/farmacologia , Rim/efeitos dos fármacos , Óxido Nítrico/fisiologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Diurese/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Isoenzimas/metabolismo , Rim/enzimologia , Rim/metabolismo , Testes de Função Renal , Masculino , NG-Nitroarginina Metil Éster/farmacologia , Natriurese/efeitos dos fármacos , Nitratos/urina , Óxido Nítrico Sintase/antagonistas & inibidores , Óxido Nítrico Sintase/metabolismo , Nitritos/urina , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Receptores do Fator Natriurético Atrial/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
Introducción Numerosos estudios sugieren que trastornos metabólicos y desequilibrios nutricionales durante la vida intrauterina pueden inducir adaptaciones que programen enfermedades cardiovasculares e hipertensión arterial. En trabajos previos mostramos que la restricción moderada de cinc durante la vida fetal, la lactancia y/o el crecimiento conduce al desarrollo de hipertensión arterial y disfunción renal en la adultez. Objetivos Evaluar la presencia de alteraciones cardiovasculares tempranas en ratas sometidas a una deficiencia moderada de cinc durante la vida fetal y la lactancia y si existen diferencias respecto del sexo. Material y métodos Ratas Wistar hembras recibieron durante la preñez hasta el destete una dieta control o baja en cinc. En el momento del nacimiento se conformaron cuatro grupos experimentales: machos y hembras nacidos de madres bajas y machos y hembras nacidos de madres controles. A los 6 y a los 21 días de vida se sacrificaron y se determinaron el peso corporal, el peso del corazón, parámetros morfométricos cardiovasculares, la actividad de la óxido nítrico sintasa en el sistema cardiovascular y el estado oxidativo cardíaco. Resultados El aporte insuficiente de cinc durante la vida fetal y la lactancia indujo un proceso de remodelación del cardiomiocito, diferente en machos que en hembras, un aumento del estrés oxidativo cardíaco, una remodelación hipotrófica de la aorta torácica y una disminución de la actividad de la óxido nítrico sintasa en el sistema cardiovascular. Conclusiones Este trabajo demuestra que la deficiencia de cinc induce alteraciones cardiovasculares, distintas en machos que en hembras, tempranas en el desarrollo, que podrían contribuir a la programación de enfermedades en la vida adulta.
Background Several studies suggest that metabolic disorders and nutrition imbalance during prenatal life may induce adaptations that program cardiovascular diseases and hypertension. We have previously shown that moderate zinc restriction during prenatal life, lactation and/or growth leads to the development of hypertension and renal dysfunction in adulthood. Objectives To evaluate the presence of early cardiovascular alterations in rats exposed to a moderate zinc deficient diet during prenatal life and lactation, and to determine whether there are differences between males and females. Material and Methods Female Wistar rats received low zinc diet or control diet from the beginning of pregnancy up to weaning. Four experimental groups were established at birth: males and females born from low-diet mothers, and males and females born from control-diet mothers. Male and female offspring were sacrificed at 6 and 21 days of life to evaluate body weight, heart weight, cardiovascular morphometric parameters and nitric oxide synthase activity in the cardiovascular system and cardiac oxidative status. Results The insufficient zinc intake during prenatal life and lacta-tion induced a remodeling process of the cardiomyocyte which was different in males and females, increased cardiac oxidative stress, produced a hypotrophic remodeling of the thoracic aorta and reduced nitric oxide synthase activity in the cardiovascular system. Conclusions This study shows that zinc deficiency induces cardiovascular abnormalities in early stages of development, which are different in males and females that may contribute to programming of diseases in adulthood.
RESUMO
Arterial blood pressure is regulated by a variety of endocrine, autocrine and neuronal systems. Natriuretic peptides and nitric oxide are important factors that exert synergistic vascular and cardiac actions and their activities are closely linked. The existence of a novel signal transduction mechanism involved in activation of nitric oxide synthase via natriuretic peptides is currently being explored. Since several cardiovascular disorders are associated with dysfunction of natriuretic peptides activity, selective modulation of the natriuretic peptides pathway represents an important therapeutic target. This review article highlights the current findings on cross-talk between natriuretic peptides and the nitric oxide system.
Assuntos
Pressão Sanguínea , Vasos Sanguíneos/fisiologia , Coração/fisiologia , Peptídeos Natriuréticos/fisiologia , Óxido Nítrico/fisiologia , Humanos , Hipotensão/fisiopatologiaRESUMO
It has been shown that angiotensin (ANG)-(1-7) activates nitric oxide synthase (NOS) in isolated ventricular myocytes from normotensive rats. Since many ANG-(1-7) actions are enhanced in situations of increased ANG II activity, as in hypertension, in this study we investigated the in vivo effect of ANG-(1-7) on NOS activity and expression of endothelial (eNOS), neuronal (nNOS), and inducible NOS (iNOS) in ventricles from spontaneously hypertensive rats (SHR). Rats were subjected to a 60-min ANG-(1-7) infusion (0.35 nmol/min); controls received saline. NOS activity was measured using the NADPH diaphorase histochemical method and by the conversion of L-[(14)C]arginine to citrulline, and NOS phosphorylation and expression were determined using Western blotting. In SHR, ANG-(1-7) infusion diminished mean arterial pressure from 180 ± 9 to 146 ± 9 mmHg (P < 0.05), and this effect was prevented by nitro-l-arginine methyl ester (l-NAME), a NOS inhibitor. In addition, NOS activity and eNOS phosphorylation were increased by ANG-(1-7) infusion. Ventricular eNOS and nNOS expression were increased 67.4 ± 6.4 and 51 ± 10%, respectively, by ANG-(1-7), whereas iNOS was not changed. In another set of experiments, we evaluated the mechanism by which ANG-(1-7) modifies NOS activity. Isolated ventricle slices preincubated with ANG-(1-7) showed an increase in NOS activity and eNOS phosphorylation, which was blocked by an AT(2) and a bradykinin B(2) receptor antagonist, but not by the Mas receptor antagonist. Our results show that in rats in a hypertensive state, ANG-(1-7) infusion upregulates cardiac NOS expression and activity through an AT(2)- and bradykinin-dependent mechanism. In this way ANG-(1-7) may elicit its cardioprotective action and contribute to some of the counterregulatory AT(2) receptor effects that oppose the AT(1) receptor-mediated effects.
Assuntos
Angiotensina I/farmacologia , Anti-Hipertensivos/farmacologia , Hipertensão/metabolismo , Miocárdio/metabolismo , Óxido Nítrico Sintase/metabolismo , Fragmentos de Peptídeos/farmacologia , Regulação para Cima/efeitos dos fármacos , Animais , Bradicinina/metabolismo , Modelos Animais de Doenças , Ventrículos do Coração/metabolismo , Masculino , Óxido Nítrico Sintase Tipo I/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Fosforilação , Ratos , Ratos Endogâmicos SHR , Receptor Tipo 2 de Angiotensina/metabolismoRESUMO
The objective was to study atrial natriuretic peptide (ANP) effects on mean arterial pressure (MAP) and cardiovascular nitric oxide (NO) system in spontaneously hypertensive rats (SHRs), investigating the receptors and signaling pathways involved. In vivo, SHRs and Wistar-Kyoto (WKY) rats were infused with saline (0.05 ml/min) or ANP (0.2 microg.kg(-1).min(-1)) for 1 h. MAP and nitrites and nitrates excretion (NOx) were determined. NO synthase (NOS) activity and endothelial (eNOS), neuronal (nNOS) and inducible (iNOS) NOS expression were measured in the heart and aorta. In vitro, heart and aortic NOS activity induced by ANP was determined in the presence of iNOS and nNOS inhibitors, natriuretic peptide receptor (NPR)-A/B blocker, G(i) protein, and calmodulin inhibitors. As a result, ANP diminished MAP and increased NOx in both groups. Cardiovascular NOS activity was higher in SHRs than in WKY rats. ANP increased NOS activity, but the activation was lower in SHRs than in WKY rats. ANP had no effect on NOS isoform expression. NOS activity induced by ANP was not modified by iNOS and nNOS inhibitors. NPR-A/B blockade blunted NOS stimulation via ANP in ventricle and aorta but not in atria. Cardiovascular NOS response to ANP was reduced by G(i) protein and calmodulin inhibitors in both groups. In conclusion, in atria, ventricle, and aorta, ANP interacts with NPR-C receptors, activating Ca(2+)-calmodulin eNOS through G(i) protein. In ventricle and aorta, NOS activation also involves NPR-A/B. The NOS response to ANP was impaired in heart and aorta of SHRs. The impaired NO-system response to ANP in hypertensive animals, involving alterations in the signaling pathway, could participate in the maintenance of high blood pressure in this model of hypertension.
Assuntos
Fator Natriurético Atrial/fisiologia , Sistema Cardiovascular/fisiopatologia , Hipertensão/fisiopatologia , Óxido Nítrico/fisiologia , Animais , Pressão Sanguínea/fisiologia , Modelos Animais de Doenças , Masculino , Miocárdio/metabolismo , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico Sintase Tipo I/metabolismo , Óxido Nítrico Sintase Tipo II/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Transdução de Sinais/fisiologiaRESUMO
Introducción Numerosos estudios mostraron que la deficiencia nutricional durante la vida fetal y posnatal predisponen al desarrollo de patologías en la vida adulta, como la hipertensión arterial y las enfermedades renales. La distribución ubicua del cinc y sus propiedades químicas determinan su esencialidad en los sistemas biológicos. Objetivos Evaluar si las alteraciones renales y cardiovasculares en la vida adulta inducidas por la restricción moderada de cinc durante la vida fetal, la lactancia y/o el crecimiento se asocian con cambios en el sistema del óxido nítrico. Material y métodos Ratas Wistar hembra recibieron durante la preñez hasta el destete de las crías una dieta control o una baja en cinc. Luego del destete, las crías macho se asignaron al azar a dos grupos que recibieron una dieta control o una baja en cinc durante 60 días. Resultados Los resultados mostraron que el aporte insuficiente de cinc durante el crecimiento previo y/o posterior al destete indujo un aumento de la presión arterial y una disminución del volumen de filtrado glomerular en la vida adulta, asociados con una disminución del sistema del óxido nítrico renal y vascular. Además, el bajo aporte de este mineral durante la vida fetal indujo un peso menor al nacer, que se correlacionó en forma negativa con la presión arterial en la vida adulta. Conclusiones Este trabajo brinda evidencias importantes que sugieren que el aporte inadecuado de cinc durante el crecimiento prenatal y posnatal constituye un factor de riesgo cardiovascular y renal, dado que induce alteraciones en la regulación de la presión arterial y en la función renal en el individuo adulto.
Background Several studies have reported that nutritional deficiencies during fetal and postnatal life predispose to the development of diseases such as hypertension and renal disorders during adulthood. The ubiquitous distribution of zinc and its chemical properties determine their essentiality in the biological systems. Objectives To assess whether renal and cardiovascular alterations induced by moderate zinc restriction during fetal life, lactation period and/or growth are associated with changes in the nitric oxide system. Material and Methods Female Wistar rats received low zinc diet or control diet from the beginning of pregnancy up to weaning. After weaning, male offspring were randomly fed with low zinc diet or control diet for 60 days. Results Zinc deficiency through pre-weaning and post-weaning growth induced increase in blood pressure and reduced glomerular filtration volume in adult life; these findings were associated with reductions in renal and vascular nitric oxide system. In addition, low zinc intake during intrauterine life induced low birth weight offspring which had a negative correlation with blood pressure in adulthood. Conclusions Zinc deficiency during prenatal and postnatal growth constitutes a risk factor for cardiovascular and kidney diseases as it induces alterations in blood pressure and renal function regulation in adult life.
RESUMO
Introducción El péptido natriurético auricular (ANP) y el óxido nítrico (NO) aumentan la diuresis y la natriuresis y disminuyen el tono vascular. Previamente demostramos que el NO está involucrado en el efecto hipotensor del ANP en ratas normotensas. Objetivo Estudiar el efecto del ANP sobre la presión arterial media (PAM) y el sistema del NO en ratas espontáneamente hipertensas (SHR) y Wistar Kyoto (WKY) y la participación de la isoforma inducible de la NO-sintasa (iNOS). Material y métodos Protocolo 1: los animales fueron infundidos con solución salina (0,05 ml/min) o con ANP (0,2 µg/kg/min) durante 1 hora. Se determinaron: PAM y nitritos y nitratos urinarios (NOx). Se extrajo el corazón y se determinaron la actividad, con L-[U14C]-arginina, y la expresión (Western blot) de iNOS y NOS endotelial (eNOS). Protocolo 2: luego del agregado de ANP (1 µM), cANP(4-23) (agonista NPR-C,1µM) o aminoguanidina (inhibidor de iNOS, 1 µM) se determinó la actividad de la NOS en la aurícula derecha y en el ventrículo izquierdo de SHR y WKY. Resultados La infusión con ANP disminuyó la PAM y aumentó los NOx en ambos grupos. La actividad NOS fue mayor en SHR y se incrementó con la infusión de ANP. Se observaron niveles proteicos mayores para eNOS e iNOS en SHR, que no se modificaron con ANP. La actividad basal de iNOS fue mayor en SHR. En la aurícula, el ANP sólo interactuaría con el NPR-C para activar la NOS y en el ventrículo también participarían los receptores NPR-A/B. El desarrollo y/o el mantenimiento de la hipertensión en este modelo experimental involucraría alteraciones en la interacción entre ambos sistemas, ANP y NO.
Background Atrial natriuretic peptide (ANP) and nitric oxide (NO) increase diuresis and natriuresis and reduce vascular tone. We have previously demonstrated that NO is involved in ANP hypotensive effect in normotensive rats. Objective To assess the effect of ANP on mean blood pressure (MBP) and on NO system in spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY), and the role of the inducible isoform of nitric oxide synthase (iNOS). Material and Methods Protocol 1: animals were instilled with saline solution (0.05 ml/min) or with ANP (0.2 µg/kg/min) for an hour. MBP and urinary nitrites and nitrates (NOx) were assessed. The heart was extracted and iNOS and endothelial iNOS (eNOS) activity (with L-[U14C]-arginine) and expression (Western blot) were determined. Protocol 2: after adding ANP (1 µM), cANP(4-23) (NPR-C agonist, 1µM) or aminoguanidine (iNOS inhibitor, 1 µM) NOS activity in the right atrium and left ventricle of SHR and WKY was determined. Results Instillation with ANP reduced MBP and increased NOx in both groups. NOS activity was greater in SHR, and increased with the instillation of ANP. In SHR, greater eNOS and iNOS protein levels were observed, which were not modified by ANP. iNOS basal activity was greater in SHR. In the atrium, ANP interacts only with NPR-C in order to activate NOS, and NPR-A/B receptors would also take part in the ventricle. In this experimental model, the development and maintenance of hypertension could involve alterations in the interaction between both systems, ANP and NO.
RESUMO
OBJECTIVE: The aim of the study was to determine the possible role of NO-system activation in vascular and renal effects of the dopaminergic system and the probable interaction between both systems during acute volume expansion in rats. DESIGN AND METHODS: Expanded (10% bw) and non-expanded anaesthetized male Wistar rats were treated with haloperidol, a DA receptor antagonist (3 mg/kg bw, ip). Mean arterial pressure, diuresis, natriuresis, renal plasma flow, glomerular filtration rate, nitrites and nitrates excretion (NOx) were determined. NADPH diaphorase activity was measured using a histochemistry technique in kidney, aorta and renal arteries. NOS activity in kidney and aorta from expanded and non-expanded animals was determined with L-[U14C]-arginine substrate, in basal conditions and after DA (1 microM) administration. RESULTS: The hypotensive effect of L-arg and hypertension induced by L-NAME were not modified by haloperidol. This blocker reverted the increase in diuresis, natriuresis and RPF induced by L-arg in both groups. Dopaminergic blockade induced a decrease in NOx excretion and in NADPH-diaphorase activity in glomeruli, proximal tubule and medullar collecting duct and in endothelium and vascular smooth muscle of renal arteries. DA induced an increase in NOS activity in renal medulla and cortex in both groups, but no changes in the aorta were observed. CONCLUSIONS: Our results suggest that renal DA would be associated with the renal response induced by NO during extracellular volume expansion. NO-system activation would be one of the mechanisms involved in renal DA activity during saline load, but NO appears not to be involved in DA vascular effects.
Assuntos
Dopamina/metabolismo , Rim/metabolismo , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico/fisiologia , Fluxo Plasmático Renal , Animais , Aorta/efeitos dos fármacos , Aorta/enzimologia , Arginina/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Citrulina/análise , Diurese/efeitos dos fármacos , Antagonistas de Dopamina/farmacologia , Líquido Extracelular/efeitos dos fármacos , Haloperidol/farmacologia , Rim/irrigação sanguínea , Rim/efeitos dos fármacos , Masculino , NADPH Desidrogenase/análise , NADPH Desidrogenase/metabolismo , NG-Nitroarginina Metil Éster/farmacologia , Natriurese/efeitos dos fármacos , Nitratos/metabolismo , Óxido Nítrico Sintase/antagonistas & inibidores , Nitritos/metabolismo , Ratos , Ratos Wistar , Artéria Renal/efeitos dos fármacos , Artéria Renal/enzimologia , Fluxo Plasmático Renal/efeitos dos fármacosRESUMO
There is an increasing interest in the involvement of trace elements such as zinc in the pathogenesis of cardiovascular diseases. This study was designed to examine whether moderate zinc deficiency during growth influences blood pressure (BP) and vascular nitric oxide (NO) pathway. Three-week-old weaned male Wistar rats were randomly divided into two dietary groups and fed either a moderately zinc-deficient diet (zinc content 9 mg/kg; n = 12) or a control diet (zinc content 30 mg/kg; n = 12) for 60 d. The following were measured: systolic BP, nitrates and nitrites urinary excretion, urinary chemiluminescence intensity, NADPH-diaphorase activity in the thoracic aorta and intestinal arterioles, and NO synthase (NOS) catalytic activity using L-[U14C]-arginine as substrate in the thoracic aorta. Zinc deficiency during growth induced an increase in BP from day 30 of the experimental period, leading to hypertension on day 60. Animals that were fed the zinc-deficient diet had lower urinary excretion levels of nitrates and nitrites and higher intensity of spontaneous luminescence on day 60. At the end of the experiment, zinc-deficient rats showed decreased NADPH diaphorase activity in endothelium and smooth muscle of the thoracic aorta and intestinal arterioles and decreased activity of NOS in thoracic aortic tissue. An imbalance in zinc bioavailability during postnatal and growing periods may be may be a risk factor in development of cardiovascular alterations in adult life. The mechanisms involved may include an impaired vascular NO system as a result of decreased NOS activity and higher systemic oxidative stress.
Assuntos
Óxido Nítrico/metabolismo , Zinco/deficiência , Zinco/metabolismo , Animais , Aorta/patologia , Aorta Torácica/metabolismo , Aorta Torácica/patologia , Arginina/química , Pressão Sanguínea , Vasos Sanguíneos/patologia , Dieta , Hipertensão , Processamento de Imagem Assistida por Computador , Mucosa Intestinal/metabolismo , Masculino , NADPH Desidrogenase/metabolismo , Óxido Nítrico Sintase/metabolismo , Estresse Oxidativo , Ratos , Ratos Wistar , Temperatura , Fatores de TempoRESUMO
En trabajos previos demostramos que la activación de la sintetasa de óxido nítrico (NOS) mediaría, al menos en parte, las acciones hipotensoras, diuréticas y natriuréticas del péptido natriurético auricular (ANP). El objetivo fue investigar el tipo de receptor natriurético y los mecanismos de señalización involucrados en la activación de la NOS en presencia de ANP. Se trabajó con aurícula, aorta y riñon de ratas Wistar macho, previamente sacrificadas por decapitación. En dichos tejidos se midió la actividad de las NOS (pmol L-[U14C] citrulina/g tejido) utilizando L-[U14C] arginina como sustrato. Tanto el ANP como el cANP (4-23) (agonista específico de receptores NPR-C) aumentaron la actividad de la NOS en todos los tejidos y este aumento fue mayor para el ANP en el riñón y la aorta y similar para ambos péptidos en la aurícula. Estos efectos fueron bloqueados por la nifedipina (bloqueante de canales de Ca²+ tipo L). La inhibición de la proteína Gi1-2 con toxina pertussis bloqueó el efecto del cANP sobre la enzima tanto en la aurícula y la arteria como en el riñón. En la aurícula, la activación de la NOS mediada por el ANP se debería a la interacción del péptido con el receptor natriurético NPR-C, mientras que en el riñón y en la aorta participarían además los receptores natriuréticos NPR-A y/o B. El ANP interactuaría con el receptor NPR-C acoplado a la vía de la proteína Gi, activando la NOS Ca²+ dependiente.
Assuntos
Masculino , Animais , Ratos , Coração , Rim , Peptídeos Natriuréticos , Óxido Nítrico Sintase , Ratos WistarRESUMO
OBJECTIVE: In previous studies we demonstrated that the administration of furosemide associated with L-arginine contributes to enhanced hypotension and induces greater water than electrolyte excretion, in both normal and expansion conditions. The aim of the present study was to elucidate the interaction between furosemide and the nitric oxide (NO) system in renal and vascular responses during extracellular volume expansion. DESIGN AND METHODS: Expanded [10% body weight (bw)] and non-expanded anaesthetized male Wistar rats were treated with furosemide (7.5 mg/kg bw). Mean arterial pressure, nitrite and nitrate excretion (NOx) were determined. NADPH-diaphorase activity, a marker of nitric oxide synthase (NOS) activity, was measured histochemically in different segments of the nephron, aorta and renal arteries. NOS activity was determined using an L-[U14C]-arginine substrate in the kidney and aorta of expanded and non-expanded rats, in basal conditions and after furosemide (10 micromol/l). RESULTS: The hypotensive effect of furosemide was enhanced when NO production was stimulated in expanded and non-expanded animals. The diuretic treatment induced a significant increase in NOx excretion, in NADPH-diaphorase activity in the thick ascending limb of Henle, renal arteries and aorta, and in NOS activity in aorta and kidney in both groups. CONCLUSIONS: Our results suggest that the hypotensive effect of furosemide may be attributed to NO-mediated vasodilation. The enhanced NOS activity, observed in the renal artery of furosemide-treated rats, could explain the increased renal plasma flow induced by furosemide. In addition, NO-pathway stimulation in the kidney could be one of the mechanisms by which furosemide exerts its diuretic and natriuretic effects, in control and in expansion conditions.