RESUMO
The aim of this work was to study the effect of a high sodium (HS) diet on blood pressure and renal function in male adult rats that have been treated with a dual Endothelin receptor antagonist (ERA) during their early postnatal period (day 1 to 20 of life). Male Sprague-Dawley rats were divided in four groups: CNS: control rats with normosodic diet; ERANS: ERA-treated rats with normosodic diet; CHS: control rats with high sodium diet; ERAHS: ERA-treated rats with HS diet. Systolic blood pressure (SBP) was recorded before and after the diet and 24-hour metabolic cage studies were performed. AQP2 and α-ENac expressions were measured by western blot and real time PCR in the renal medulla. Vasopressin (AVP) pathway was evaluated by measuring V2 receptor and adenylyl cyclase 6 (AC6) expression and cAMP production in the renal medulla. Pre-pro ET-1mRNA was also evaluated in the renal medulla. Only rats that had been treated with an ERA during their postnatal period increased their SBP after consumption of a HS diet, showing an impaired capacity to excrete sodium and water, i.e. developing salt sensitivity. This salt sensitivity would be mediated by an increase in renomedullary expression and activity of AQP2 and α-ENaC as a consequence of increased AC6 expression and cAMP production and/or a decreased ET-1 production in the renal medulla. The knowledge of the molecular mechanisms underlying the perinatal programming of salt sensitive hypertension will allow the development of reprogramming strategies in order to avoid this pathology.
Assuntos
Endotelinas/metabolismo , Hipertensão/etiologia , Medula Renal/crescimento & desenvolvimento , Receptores de Endotelina/metabolismo , Transdução de Sinais/fisiologia , Adulto , Animais , Animais Recém-Nascidos , Aquaporina 2/metabolismo , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Modelos Animais de Doenças , Antagonistas dos Receptores de Endotelina/farmacologia , Endotelinas/antagonistas & inibidores , Canais Epiteliais de Sódio/metabolismo , Humanos , Hipertensão/fisiopatologia , Recém-Nascido , Medula Renal/efeitos dos fármacos , Masculino , Ratos , Ratos Sprague-Dawley , Eliminação Renal/efeitos dos fármacos , Eliminação Renal/fisiologia , Transdução de Sinais/efeitos dos fármacos , Cloreto de Sódio na Dieta/efeitos adversos , Cloreto de Sódio na Dieta/metabolismo , Vasopressinas/metabolismoRESUMO
The aim of this project was to investigate the interaction between the calcium-sensing receptor (CaSR) and proton extrusion by the V-ATPase and gastric-like isoform of the H(+)/K(+)-ATPase in the mouse nephron. Biochemical activity of H(+)- ATPases was analysed using a partially purified membrane fraction of mouse cortex and outer medullary region. The V-ATPase activity (sensitive to 10(-7) mol·L(-1) bafilomycin) from the cortical and outer medullary region was significantly stimulated by increasing the [Formula: see text] (outside Ca(2+)), in a dose-dependent pattern. Gastric H(+)/K(+)-ATPase activity (sensitive to 10(-5) mol·L(-1) Schering 28080) was also sensitive to changes in [Formula: see text] levels. A significant increase in V-ATPase activity was also observed when CaSR was stimulated with agonists such as 300 µmol·L(-1) Gd(3+) and 200 µmol·L(-1) neomycin, both in the cortex and outer medulla. The cortical and outer medullary gastric H(+)/K(+)-ATPase activity was also stimulated by Gd(3+) and neomycin. Finally, cortical V-ATPase activity was significantly stimulated by 10(-9) mol·L(-1) angiotensin II, and the stimulation of CaSR in the presence of angiotensin significantly enhanced this effect, suggesting that an interaction in the intracellular signaling pathways is involved. In summary, CaSR stimulation enhances the biochemical activity of V-ATPase and gastric H(+)/K(+)-ATPase in both the cortical and outer medullary region of mouse kidney.
Assuntos
ATPase Trocadora de Hidrogênio-Potássio/metabolismo , Córtex Renal/metabolismo , Medula Renal/metabolismo , Receptores de Detecção de Cálcio/agonistas , ATPases Vacuolares Próton-Translocadoras/metabolismo , Angiotensina II/farmacologia , Animais , Cálcio/metabolismo , Gadolínio/farmacologia , Isoenzimas/metabolismo , Córtex Renal/efeitos dos fármacos , Medula Renal/efeitos dos fármacos , Camundongos , Neomicina/farmacologiaRESUMO
In the present study, we investigated the in vitro effect of hypoxanthine on the activities of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase, as well as on thiobarbituric-acid-reactive substances (TBA-RS), in the renal cortex and medulla of rats. Results showed that hypoxanthine, at a concentration of 10.0 µM, enhanced the activities of CAT and SOD in the renal cortex of 15-, 30- and 60-day-old rats, enhanced SOD activity in the renal medulla of 60-day-old rats and enhanced TBA-RS levels in the renal medulla of 30-day-old rats, as compared with controls. Furthermore, we also verified the influence of allopurinol (an inhibitor of xanthine oxidase), as well as of the antioxidants, trolox and ascorbic acid on the effects elicited by hypoxanthine on the parameters tested. Allopurinol and/or administration of antioxidants prevented most alterations caused by hypoxanthine in the oxidative stress parameters evaluated. Data suggest that hypoxanthine alters antioxidant defences and induces lipid peroxidation in the kidney of rats; however, in the presence of allopurinol and antioxidants, some of these alterations in oxidative stress were prevented. Our findings lend support to a potential therapeutic strategy for this condition, which may include the use of appropriate antioxidants for ameliorating the damage caused by hypoxanthine.
Assuntos
Alopurinol/farmacologia , Antioxidantes/farmacologia , Ácido Ascórbico/farmacologia , Hipoxantina/farmacologia , Córtex Renal/efeitos dos fármacos , Medula Renal/efeitos dos fármacos , Oxidantes/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Vitamina E/farmacologia , Animais , Córtex Renal/metabolismo , Medula Renal/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Ratos WistarRESUMO
During renin-angiotensin system activation, cyclooxygenase-2 (COX-2)-derived prostaglandins attenuate the pressor and antinatriuretic effects of angiotensin II (AngII) in the renal medulla. The (pro)renin receptor (PRR) is abundantly expressed in the collecting ducts (CD) and its expression is augmented by AngII. PRR overexpression upregulates COX-2 via mitogen-activated kinases/extracellular regulated kinases 1/2 in renal tissues; however, it is not clear whether this effect occurs independently or in concert with AngII type 1 receptor (AT1R) activation. We hypothesized that PRR activation stimulates COX-2 expression independently of AT(1)R in primary cultures of rat renal inner medullary cells. The use of different cell-specific immunomarkers (aquaporin-2 for principal cells, anion exchanger type 1 for intercalated type-A cells, and tenascin C for interstitial cells) and costaining for AT(1)R, COX-2, and PRR revealed that PRR and COX-2 were colocalized in intercalated and interstitial cells whereas principal cells did not express PRR or COX-2. In normal rat kidney sections, PRR and COX-2 were colocalized in intercalated and interstitial cells. In rat renal inner medullary cultured cells, treatment with AngII (100 nmol/L) increased COX-2 expression via AT(1)R. In addition, AngII and rat recombinant prorenin (100 nmol/L) treatments increased extracellular regulated kinases 1/2 phosphorylation, independently. Importantly, rat recombinant prorenin upregulated COX-2 expression in the presence of AT(1)R blockade. Inhibition of mitogen-activated kinases/extracellular regulated kinases 1/2 suppressed COX-2 upregulation mediated by either AngII or rat recombinant prorenin. Furthermore, PRR knockdown using PRR-short hairpin RNA blunted the rat recombinant prorenin-mediated upregulation of COX-2. These results indicate that COX-2 expression is upregulated by activation of either PRR or AT(1)R via mitogen-activated kinases/extracellular regulated kinases 1/2 in rat renal inner medullary cells.
Assuntos
Angiotensina II/farmacologia , Ciclo-Oxigenase 2/metabolismo , Medula Renal/metabolismo , Receptores de Superfície Celular/metabolismo , Sistema Renina-Angiotensina/fisiologia , Animais , Células Cultivadas , Ciclo-Oxigenase 2/genética , Medula Renal/citologia , Medula Renal/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/fisiologia , Fosforilação/efeitos dos fármacos , Ratos , Receptor Tipo 1 de Angiotensina/genética , Receptor Tipo 1 de Angiotensina/metabolismo , Receptores de Superfície Celular/genética , Sistema Renina-Angiotensina/efeitos dos fármacos , Regulação para Cima , Receptor de Pró-ReninaRESUMO
We investigated captopril effects, an ACE inhibitor, on hypertension development, on Ang II and Ang-(1-7) plasma concentrations, on Ang II-induced contraction in isolated kidneys, and on kidney AT1R from spontaneously hypertensive (SHR) rats. Five weeks-old SHR and Wistar Kyoto (WKY) rats were treated with captopril at 30 mg/kg/day, in drinking water for 2 or 14 weeks. Systolic blood pressure (SBP) was measured, and isolated kidneys were tested for perfusion pressure and AT1R expression; while Ang II and Ang-(1-7) concentrations were determined in plasma. Captopril did not modify SBP in WKY rats and avoided its increase as SHR aged. Plasma Ang-II concentration was â¼4-5 folds higher in SHR rats, and captopril reduced it (P<0.05); while captopril increased Ang-(1-7) by â¼2 fold in all rat groups. Captopril increased Ang II-induced pressor response in kidneys of WKY and SHR rats, phenomenon not observed in kidneys stimulated with phenylephrine, a α1-adrenoceptor agonist. Captopril did not modify AT1R in kidney cortex and medulla among rat strains and ages. Data indicate that captopril increased Ang II-induced kidney perfusion pressure but not AT1R density in kidney of WKY and SHR rats, due to blockade of angiotensin II synthesis; however, ACE inhibitors may have other actions like activating signaling processes that could contribute to their diverse effects.
Assuntos
Angiotensina II/sangue , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Captopril/uso terapêutico , Hipertensão/prevenção & controle , Rim/efeitos dos fármacos , Pré-Hipertensão/tratamento farmacológico , Resistência Vascular/efeitos dos fármacos , Envelhecimento , Angiotensina I/sangue , Angiotensina II/metabolismo , Inibidores da Enzima Conversora de Angiotensina/efeitos adversos , Animais , Anti-Hipertensivos/efeitos adversos , Anti-Hipertensivos/uso terapêutico , Pressão Sanguínea/efeitos dos fármacos , Captopril/efeitos adversos , Hipertensão/etiologia , Rim/irrigação sanguínea , Rim/metabolismo , Rim/fisiopatologia , Córtex Renal/efeitos dos fármacos , Córtex Renal/metabolismo , Medula Renal/efeitos dos fármacos , Medula Renal/metabolismo , Masculino , Fragmentos de Peptídeos/sangue , Pré-Hipertensão/sangue , Pré-Hipertensão/metabolismo , Pré-Hipertensão/fisiopatologia , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Receptor Tipo 1 de Angiotensina/metabolismo , Organismos Livres de Patógenos EspecíficosRESUMO
BACKGROUND: Ischemia-reperfusion (I/R) injury is one of the risk factors for delayed graft function, acute rejection episodes, and impaired long-term allograft survival after kidney transplantation. This antigen-independent inflammatory process produces tissue damage. Isogeneic transplantation in a rat model is a useful method for study of nonimmunologic risk factors for kidney damage. OBJECTIVE: To study the effect of sirolimus on I/R injury using only 1 dose of the drug in the donor. MATERIALS AND METHODS: Eighteen rats were allocated to 3 groups of 6 rats each: sham group, control group, and rapamycin group. RESULTS: Improved renal function and systemic inflammatory response were observed in the rapamycin group compared with the control group (Deltaurea, Deltacreatinine, and DeltaC3, all P < .01). The number of apoptotic nuclei in the renal medulla in the control group was higher than in the rapamycin group (P < .01). Tubular damage was less severe in the rapamycin group compared with the control group (P < .01). Complement 3 and tumor necrosis factor-alpha expression in the kidney samples were significantly decreased when rapamycin was given to the donor rats (P > .01). Bcl-2 protein was upregulated in the rapamycin group compared with the control group (P < .01). CONCLUSION: Administration of rapamycin in donors attenuates the I/R injury process after kidney transplantation in a rat model.
Assuntos
Imunossupressores/uso terapêutico , Transplante de Rim/imunologia , Sirolimo/uso terapêutico , Animais , Complemento C3/genética , Creatinina/sangue , Regulação da Expressão Gênica/efeitos dos fármacos , Testes de Função Renal , Medula Renal/efeitos dos fármacos , Transplante de Rim/patologia , Transplante de Rim/fisiologia , Masculino , Modelos Animais , Ratos , Ratos Wistar , Fator de Necrose Tumoral alfa/genética , Ureia/sangue , Ureia/metabolismoRESUMO
This study was undertaken in anesthetized dogs to evaluate the relative participation of prostaglandins (PGs) and nitric oxide (NO) in the maintenance of total renal blood flow (TRBF), and renal medullary blood flow (RMBF). It was hypothesized that the inhibition of NO should impair cortical and medullary circulation because of the synthesis of this compound in the endothelial cells of these two territories. In contrast, under normal conditions of perfusion pressure PG synthesis is confined to the renal medulla. Hence PG inhibition should predominantly impair the medullary circulation. The initial administration of 25 microM kg-1 min-1 NG-nitro-L-arginine methyl ester produced a significant 26% decrease in TRBF and a concomitant 34% fall in RMBF, while the subsequent inhibition of PGs with 5 mg/kg meclofenamate further reduced TRBF by 33% and RMBF by 89%. In contrast, the initial administration of meclofenamate failed to change TRBF, while decreasing RMBF by 49%. The subsequent blockade of NO decreased TRBF by 35% without further altering RMBF. These results indicate that initial PG synthesis inhibition predominantly alters the medullary circulation, whereas NO inhibition decreases both cortical and medullary flow. This latter change induced by NO renders cortical and RMBF susceptible to a further decrease by PG inhibition. However, the decrease in medullary circulation produced by NO inhibition is not further enhanced by subsequent PG inhibition.
Assuntos
Córtex Renal/irrigação sanguínea , Medula Renal/irrigação sanguínea , Óxido Nítrico/fisiologia , Prostaglandinas/fisiologia , Animais , Bradicinina/farmacologia , Inibidores de Ciclo-Oxigenase/farmacologia , Cães , Córtex Renal/efeitos dos fármacos , Medula Renal/efeitos dos fármacos , Masculino , Ácido Meclofenâmico/farmacologia , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico/antagonistas & inibidores , Antagonistas de Prostaglandina/farmacologia , Fluxo Sanguíneo Regional/efeitos dos fármacos , Vasodilatadores/farmacologiaRESUMO
This study was undertaken in anesthetized dogs to evaluate the relative participation of prostaglandins (PGs) and nitric oxide (NO) in the maintenance of total renal blood flow (TRBF), and renal medullary blood flow (RMBF). It was hypothesized that the inhibition of NO should impair cortical and medullary circulation because of the synthesis of this compound in the endothelial cells of these two territories. In contrast, under normal conditions of perfusion pressure PG synthesis is confined to the renal medulla. Hence PG inhibition should predominantly impair the medullary circulation. The initial administration of 25 µM kg-1 min-1 NG-nitro-L-arginine methyl ester produced a significant 26 percent decrease in TRBF and a concomitant 34 percent fall in RMBF, while the subsequent inhibition of PGs with 5 mg/kg meclofenamate further reduced TRBF by 33 percent and RMBF by 89 percent. In contrast, the initial administration of meclofenamate failed to change TRBF, while decreasing RMBF by 49 percent. The subsequent blockade of NO decreased TRBF by 35 percent without further altering RMBF. These results indicate that initial PG synthesis inhibition predominantly alters the medullary circulation, whereas NO inhibition decreases both cortical and medullary flow. This latter change induced by NO renders cortical and RMBF susceptible to a further decrease by PG inhibition. However, the decrease in medullary circulation produced by NO inhibition is not further enhanced by subsequent PG inhibition.
Assuntos
Animais , Cães , Masculino , Córtex Renal/irrigação sanguínea , Medula Renal/irrigação sanguínea , Óxido Nítrico/fisiologia , Prostaglandinas/fisiologia , Bradicinina/farmacologia , Inibidores de Ciclo-Oxigenase/farmacologia , Córtex Renal/efeitos dos fármacos , Medula Renal/efeitos dos fármacos , Ácido Meclofenâmico/farmacologia , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico/antagonistas & inibidores , Antagonistas de Prostaglandina/farmacologia , Fluxo Sanguíneo Regional/efeitos dos fármacos , Vasodilatadores/farmacologiaRESUMO
AIM: To standardize microdialysis in rat kidneys and address cyclosporine A (CsA) effects on renal cortex and medulla interstitial glucose. METHODS: Munich-Wistar rats were treated with vehicle or CsA (15 mg/kg/day) for 3 weeks. Glucose was assessed by spectrophotometry in dialysate samples from cortex, medulla and arterial plasma. Plasma insulin was measured by radioimmunoassay. Renal blood flow (RBF) was measured by Doppler ultrasound. Creatinine and urea were measured by spectrophotometry. RESULTS: CsA significantly increased the plasma levels of urea and creatinine (1.5 +/- 0.20 vs. 0.73 +/- 0.03 mg/dl in controls, p < 0.05). Medullary glucose in control was 44% lower than arterial glucose (56 +/- 6 vs. 101 +/- 8 mg/dl, p < 0.05). At the same time, CsA increased arterial (163 +/- 35 vs. 101 +/- 8 mg/dl in controls, p < 0.05) and medullary interstitial glucose (100 +/- 18 vs. 56 +/- 6 mg/dl in controls, p < 0.05), but did not affect cortical glucose (114 +/- 21 vs. 90 +/- 11 mg/dl in controls). These changes occurred in the presence of a decreased plasma insulin level (2.7 +/- 0.2 vs. 9.3 +/- 0.4 microU/ml in controls, p < 0.05). The increment in medullary glucose in CsA group occurred despite a reduction in RBF (4.6 +/- 0.8 vs. 6.5 +/- 1.0 ml/min/kidney in controls, p < 0.05). CONCLUSIONS: Microdialysis was an adequate tool to investigate in vivo regulation of renal glucose metabolism. Renal glucose uptake was dependent on medullary cells and CsA treatment induced diabetogenic effects on renal medulla in situ.
Assuntos
Glicemia/metabolismo , Ciclosporina/farmacologia , Imunossupressores/farmacologia , Córtex Renal/efeitos dos fármacos , Medula Renal/efeitos dos fármacos , Animais , Cateterismo , Córtex Renal/irrigação sanguínea , Medula Renal/irrigação sanguínea , Masculino , Microdiálise/métodos , Microdiálise/normas , Ratos , Ratos WistarRESUMO
Cyclosporin, an immunosuppressive drug, is known to affect macrophage and to exert a nephrotoxic effect. Aminopeptidases play important roles for renal and macrophage functions. In this work, we attempt to test the hypothesis that the aminopeptidases participate within macrophage and renal effects induced by cyclosporin. Macrophage and renal aminopeptidase activities of cyclosporin-treated and control mice were evaluated, as well as renal caspase 3 activity, hematocrit, urinary protein and plasma osmolality, creatinine and uric acid concentrations. Cyclosporin treatment increased caspase 3 activity, hematocrit and osmolality, while urinary protein, creatinine and uric acid were unaltered. Soluble and particulate aminopeptidases in resident and elicited macrophages were unaffected by cyclosporin. The treatment with cyclosporin increased neutral, basic, cystyl, prolyl imino and pyroglutamyl soluble aminopeptidase activities in the renal cortex. Acid and basic soluble aminopeptidase activities increased in the renal medulla. Increased levels of particulate form in the cortex were detected for acid and pyroglutamyl aminopeptidase activities. Cyclosporin increased cortical soluble while decreased medullar particulate prolyl dipeptidyl aminopeptidase IV activity. With the exception of prolyl dipeptidyl aminopeptidase IV, particulate aminopeptidase activities returned to levels similar to controls after fifteen days of cyclosporin withdrawal, and soluble aminopeptidase activities did not regress. Our data indicate that the adopted regimen of cyclosporin treatment produced mild renal impairment with consistent changes on the levels of renal but not macrophage aminopeptidase activities. The obtained profiles of macrophage and renal aminopeptidase activities should be considered into the elaboration of new potential strategies for preventing nephrotoxicity during the treatment with cyclosporin.
Assuntos
Aminopeptidases/metabolismo , Ciclosporina/farmacologia , Imunossupressores/farmacologia , Rim/efeitos dos fármacos , Rim/enzimologia , Macrófagos/efeitos dos fármacos , Macrófagos/enzimologia , Animais , Ciclosporina/administração & dosagem , Ativação Enzimática/efeitos dos fármacos , Imunossupressores/administração & dosagem , Córtex Renal/efeitos dos fármacos , Córtex Renal/enzimologia , Medula Renal/efeitos dos fármacos , Medula Renal/enzimologia , L-Lactato Desidrogenase/urina , Masculino , CamundongosRESUMO
The identification and cloning of the urea transporter (UT) in papilla and upper pelvic epithelium of sheep kidney and the effect of a 5-week-lasting low protein diet on UT mRNAs expression in these structures are reported. Using degenerate primers we cloned by RT-PCR a 770-base pairs UT-A cDNA fragment. The deduced amino acid sequence shared 92% and 93% identity with UT-A2 protein from rabbit and rat, and from human, respectively. Quantification of UT-A mRNAs expression after LP diet was performed by quantitative RT-PCR using UT-A mutant cRNA. Compared to normal protein fed sheep, low protein diet was associated with a significant reduction of UT-A mRNA levels in pelvic epithelium (852+/-172 vs. 2024+/-260 molecules, P<0.01) and a tendency to its increase in papilla (7959+/-1741 vs. 5447+/-1040 molecules, NS). Functional studies confirmed that kidneys of low protein fed sheep increased their ability to reduce urea losses. The reduction of UT-A expression in the pelvic epithelium lining the outer medulla could be relevant for the renal conservation of urea in protein restricted sheep.
Assuntos
Proteínas Alimentares/administração & dosagem , Proteínas Alimentares/farmacologia , Epitélio/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Medula Renal/efeitos dos fármacos , Proteínas de Membrana Transportadoras/genética , Carneiro Doméstico/genética , Sequência de Aminoácidos , Animais , Clonagem Molecular , Epitélio/metabolismo , Feminino , Medula Renal/metabolismo , Proteínas de Membrana Transportadoras/química , Dados de Sequência Molecular , Pelve , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Homologia de Sequência de Aminoácidos , Carneiro Doméstico/metabolismo , Transportadores de UreiaRESUMO
Previous works from our laboratory demonstrated that PGD(2) modulates phosphatidylcholine (PC) biosynthesis in renal papillary tissue. In the present work, we have evaluated the mechanism by which PGD(2) exerts this action. PGD(2) caused two stimulatory waves in PC synthesis which were reproduced by its full-agonist BW245C. At 1min stimulation, PGD(2) increased PC synthesis by 131%; this increase was blocked by neomycin and ethanol, cheleritrine and U0126, PLD, PKC, and MEK1/2 inhibitors, respectively. A second PC synthesis increase (100%) was observed after 15min, which was blocked by PLD inhibitors. PGD(2) also increased phospho-ERK1/2 MAPK in a biphasic-fashion, which was abolished by PLC and PKC inhibitors but not by ethanol, which overincreased phospho-ERK1/2, suggesting that PGD(2)-induced ERK1/2 activation requires previous PLC-PKC activation while PLD down-regulates it. Our results indicate that PGD(2) stimulatory effect involves both PLD and ERK1/2-MAPK activation, and both pathways operate independently of PC synthesis homeostasis.
Assuntos
Homeostase/fisiologia , Medula Renal/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosfatidilcolinas/biossíntese , Fosfolipase D/metabolismo , Prostaglandina D2/farmacologia , Animais , Membrana Celular/metabolismo , Técnicas de Cultura , Ativação Enzimática/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Humanos , Medula Renal/efeitos dos fármacos , Masculino , Taxa de Depuração Metabólica , Proteína Quinase 1 Ativada por Mitógeno/efeitos dos fármacos , Proteína Quinase 3 Ativada por Mitógeno , Proteínas Quinases Ativadas por Mitógeno/efeitos dos fármacos , Fosfolipase D/efeitos dos fármacos , Ratos , Ratos WistarRESUMO
Atrial natriuretic peptide (ANP) and nitric oxide (NO) induce diuresis, natriuresis and diminish vascular tone. Our previous studies showed NO system is involved in ANP hypotensive effect. The aim was to investigate ANP effects on renal and cardiac NO-synthase (NOS) activity. Rats were divided into two groups: group I, infused with saline (1 h, 0.05 ml/min); group II, received ANP bolus (5 microg/kg)+ANP infusion (1 h, 0.2 microg/kg x min). NADPH-diaphorase activity (NADPH-d) was determined in kidney and heart. NOS catalytic activity was determined in renal medulla and cortex and cardiac atria and ventricle by measuring the conversion of l-[U(14)C]-arginine to l-[U(14)C]-citrulline. In group I, NOS activity was determined in basal conditions and plus 1 microM ANP and in group II, NOS activity was determined in basal conditions. NADPH-d was higher in group II than in group I in glomeruli, proximal tubule, cortical and medullar collecting duct, right atria and left ventricle. NOS activity was increased by in vitro ANP addition and, in vivo, ANP infusion in all the studied tissues. ANP treatment increases renal and cardiac NO synthesis. This effect would be independent on the hemodynamic changes induced by ANP. The activation of NO pathway would be one of the mechanisms involved in diuretic, natriuretic and hypotensive effects of ANP.
Assuntos
Fator Natriurético Atrial/fisiologia , Coração/fisiologia , Rim/metabolismo , Óxido Nítrico Sintase/metabolismo , Animais , Fator Natriurético Atrial/farmacologia , Coração/efeitos dos fármacos , Átrios do Coração/efeitos dos fármacos , Átrios do Coração/enzimologia , Átrios do Coração/metabolismo , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/enzimologia , Ventrículos do Coração/metabolismo , Histocitoquímica , Rim/efeitos dos fármacos , Rim/enzimologia , Córtex Renal/efeitos dos fármacos , Córtex Renal/enzimologia , Córtex Renal/metabolismo , Medula Renal/efeitos dos fármacos , Medula Renal/enzimologia , Medula Renal/metabolismo , Masculino , Miocárdio/enzimologia , Miocárdio/metabolismo , NADPH Desidrogenase/análise , NADPH Desidrogenase/metabolismo , NG-Nitroarginina Metil Éster/farmacologia , Néfrons/efeitos dos fármacos , Néfrons/enzimologia , Néfrons/metabolismo , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase/análise , Óxido Nítrico Sintase/antagonistas & inibidores , Ratos , Ratos WistarRESUMO
The possibility of gender differences in the relationship between dose and efficacy of drugs has historically been limited. The aim of the present study was to evaluate the influence of sex on the pharmacodynamics of furosemide (FUR) in adult Wistar rats. Conventional renal clearance studies were performed in the absence and in the presence of a FUR dose necessary to produce identical urine excretion rates of FUR in both sexes. Fractional excretions of sodium, potassium, and water were similar in male and female rats in the absence of FUR. Natriuretic, kaliuretic, and diuretic responses to FUR, when expressed in fractional terms, were significantly increased in female rats. Diuretic, natriuretic, and kaliuretic efficiencies of FUR were also higher in female rats as compared with males. This might be explained by the lower abundance of the Na-K-2Cl cotransporter observed in homogenates from the medullae of female kidneys as compared with male ones.
Assuntos
Diuréticos/farmacologia , Diuréticos/farmacocinética , Furosemida/farmacologia , Furosemida/farmacocinética , Animais , Pressão Sanguínea/efeitos dos fármacos , Feminino , Taxa de Filtração Glomerular , Córtex Renal/efeitos dos fármacos , Córtex Renal/metabolismo , Testes de Função Renal , Medula Renal/efeitos dos fármacos , Medula Renal/metabolismo , Túbulos Renais Proximais/metabolismo , Masculino , Potássio/urina , Ratos , Ratos Wistar , Caracteres Sexuais , Sódio/urina , Simportadores de Cloreto de Sódio-Potássio/metabolismo , Urodinâmica/efeitos dos fármacosRESUMO
Sodium transport correlates with varying Na+-K+-ATPase activity rates along the nephron. Whether differences in Na+-K+-ATPase regulation by protein kinase C-dependent phosphorylation are also present has not been tested. We measured the degree of Na+-K+-ATPase alpha1 subunit phosphorylation by the binding of McK-1 antibody to dephosphorylated Ser-23 and Na+-K+-ATPase activity in medullary thick ascending limb of Henle (mTAL) and proximal tubules (PCT). The degree of Na+-K+-ATPase phosphorylation at Ser-23 was lower in mTAL than in PCT (DU 13.43+/-1.99 versus 2.3+/-0.20, respectively, P<0.01) while Na+-K+-ATPase activity was higher in mTAL (3,402+/-83 vs 711+/-158 pmol/mm tubule per hour in PCT, P<0.01). PKC inhibitor RO-318220 10(-6) M decreased phosphorylation in PCT to 125+/-10% ( P<0.05). In mTAL, RO-318220 did not modify the phosphorylation degree or the activity of Na+-K+-ATPase. Both calcineurin inhibitor FK-506 10(-6) M and phorbol 12-myristate 13-acetate (PMA) 10(-6) M increased the degree of Na+-K+-ATPase phosphorylation ( P<0.05) and inhibited Na+-K+-ATPase activity to 657+/-152 and 1,448+/-347 pmol/mm tubule per hour, respectively, in mTAL ( P<0.01). Increase in [Na+]i to 30, 50 and 70 mM resulted in no changes in Na+-K+-ATPase phosphorylation degree or activity in mTAL. Conversely, in PCT increments in [Na+]i were paralleled by decreased phosphorylation (from 120+/-7 to 160+/-15% of controls, P<0.05) and increased Na+-K+-ATPase activity (from 850+/-139 to 1,874+/-203 pmol/mm tubule per hour, P<0.01). Dopamine (DA) 10(-6) M decreased both Na+-K+-ATPase dephosphorylation to 41.85+/-9.58% ( P<0.05) and Na+-K+-ATPase activity to 2,405+/-176 pmol/mm tubule per hour in mTAL ( P<0.01). RO-318220 reversed DA effects. Data suggest that regulation of the degree of Na+-K+-ATPase alpha1 subunit phosphorylation at Ser-23 and enzyme activity have different mechanisms in mTAL than in PCT, and may help us to understand the physiological heterogeneity of both segments.
Assuntos
Medula Renal/enzimologia , Alça do Néfron/enzimologia , Proteína Quinase C/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Animais , Inibidores Enzimáticos/farmacologia , Medula Renal/efeitos dos fármacos , Alça do Néfron/efeitos dos fármacos , Masculino , Fosforilação/efeitos dos fármacos , Proteína Quinase C/antagonistas & inibidores , Ratos , Ratos Wistar , ATPase Trocadora de Sódio-Potássio/antagonistas & inibidoresRESUMO
It is well known that Na+ reabsorption in the kidney can be regulated by aldosterone. Although Cl- is the most abundant anion present in the extra cellular fluids the involvement of aldosterone in the regulation of Cl- conductance through Cl- channels at the molecular level is unknown. In this study, the effects of aldosterone and high-Na+ diet on the expression of ClC-2, a cell volume-, pH- and voltage-sensitive Cl- channel, was examined in the rat kidney. Total RNA isolated from Wistar rats fed a high-Na+ diet for 5 days, furosemide treatment, adrenalectomy and adrenalectomy with replacement of normal plasma levels of aldosterone were compared by the use of ribonuclease protection assay (RPA), and/or a semi-quantitative RT-PCR. The high-Na+ diet reduced renal mRNA and protein ClC-2 expression. The renal expression of ClC-2 mRNA decreased in adrenalectomized rats and was restored by plasma aldosterone replacement. In addition, the semi-quantitative RT-PCR in different segments of the nephron showed that these changes were secondary to the modulation of ClC-2 mRNA expression by aldosterone in the cortical and medullary segments of thick ascending limbs of Henle's loop. These results suggest that ClC-2 may be involved with aldosterone-induced Cl- transport in the kidney.
Assuntos
Aldosterona/farmacologia , Canais de Cloreto/biossíntese , Canais de Cloreto/genética , Rim/metabolismo , Cloreto de Sódio na Dieta/farmacologia , Adrenalectomia , Animais , Southern Blotting , Western Blotting , Diuréticos/farmacologia , Eletrólitos/metabolismo , Furosemida/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Rim/efeitos dos fármacos , Córtex Renal/efeitos dos fármacos , Córtex Renal/metabolismo , Medula Renal/efeitos dos fármacos , Medula Renal/metabolismo , Masculino , Néfrons/efeitos dos fármacos , Néfrons/metabolismo , Ensaios de Proteção de Nucleases , RNA/biossíntese , RNA/genética , Ratos , Ratos Wistar , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Chronic ethanol exposure causes alterations in biologic membranes of different cell types. (Na + K) adenosine triphosphatase (ATPase), a membrane-bound enzyme inhibited by the acute presence of ethanol, increases its activity in rat kidney after chronic ethanol consumption. The aim of this investigation was to evaluate the effect of ethanol on the modulation of (Na + K)-ATPase by glucocorticoids and mineralocorticoids in renal papillary collecting duct cells. Cultured renal papillary collecting duct cells were exposed to a medium containing 150 mM ethanol plus either 100 nM aldosterone or 10 nM dexamethasone. Control groups were cultured in the absence of ethanol and/or the hormones. Mg(2+)-ATPase was used as control enzyme. The activity of ATPases was measured by ATP hydrolysis. Ethanol increased the activities of (Na + K)-ATPase and Mg(2+)- ATPase in 29 and 33% of controls, respectively; only (Na + K)-ATPase activity was elevated in the presence of aldosterone or dexamethasone, whereas Mg(2+)-ATPase was unaltered by these hormones. The effects of aldosterone and dexamethasone on (Na + K)-ATPase activity were augmented by ethanol in 50 and 19% of controls, respectively. These results suggest that ethanol treatment enhances the upregulation of (Na + K)-ATPase activity by both aldosterone and dexamethasone, in cultured renal papillary collecting duct cells.
Assuntos
Aldosterona/farmacologia , Dexametasona/farmacologia , Etanol/farmacologia , Medula Renal/enzimologia , Túbulos Renais Coletores/enzimologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , ATPase de Ca(2+) e Mg(2+)/metabolismo , Células Cultivadas , Glucocorticoides/farmacologia , Homeostase/efeitos dos fármacos , Medula Renal/efeitos dos fármacos , Túbulos Renais Coletores/efeitos dos fármacos , Masculino , Ratos , Ratos WistarRESUMO
The effects of a high glucose concentration (HGC) on renal phosphatidylcholine (PtdCho) biosynthesis were studied. In control rats, HGC increased papillary PtdCho biosynthesis. In chronic diabetic rats, an increase above that induced by diabetes was observed. Such glucose-responsive phospholipid pools were shown to be transient in adult control rats, while in acute diabetic and aged control and chronic diabetic rats they seem to be of slow breakdown or permanent. Deoxyglucose evokes the HGC effect only in the presence of 5 mM glucose. Neomycin, which blocks phospholipase C action, corrected the HGC effect in control and chronic diabetic rats, but not the increase due to diabetes. CDP-choline: 1,2-diacylglycerol cholinephosphotransferase activity was increased by both in vivo and simulated diabetes. Therefore, transient high extracellular glucose levels promote a reversible increase in papillary (32)P-PtdCho, while diabetes causes an irreversible increase resulting in PtdCho accumulation, possibly related to papillary necrosis.
Assuntos
Glicemia/metabolismo , Diabetes Mellitus Experimental/metabolismo , Medula Renal/metabolismo , Fosfatidilcolinas/biossíntese , Animais , Desoxiglucose/metabolismo , Medula Renal/efeitos dos fármacos , Masculino , Microssomos/metabolismo , Neomicina/farmacologia , Fosfatidilcolinas/metabolismo , Ratos , Ratos WistarRESUMO
Cyclosporine toxicity mainly affects kidney and liver function. We have previously shown that cyclosporine nephrotoxicity alters kidney nitric oxide synthase mRNA pattern of expression. To determine if nitric oxide synthase expression changes are mediated directly by cyclosporine or by secondary hemodynamic alterations induced by cyclosporine, we evaluated if these effects are tissue specific and if nifedipine-induced vasodilation prevents these alterations. Uninephrectomized Wistar rats treated for 7 days with olive oil, cyclosporine (30 mg/kg), nifedipine (3 mg/kg), and nifedipine+cyclosporine were studied. In vehicle and cyclosporine groups, the gene expression of the neuronal, inducible, and endothelial nitric oxide synthases in cerebellum, heart, intestine, liver, renal cortex, and medulla was evaluated. The administration of cyclosporine was associated with nephrotoxicity and hepatotoxicity, increased endothelial nitric oxide synthase mRNA levels in renal cortex and liver, and a decrease in inducible nitric oxide synthase and neuronal nitric oxide synthase in renal medulla. The mRNA levels of the 3 nitric oxide synthase isoforms were not affected in any other tissue. Nifedipine did not alter nitric oxide synthase expression in the control group but prevented changes associated with cyclosporine. These results suggest that cyclosporine-induced changes in the pattern of expression of the nitric oxide synthases may be secondary to its hemodynamic effects.
Assuntos
Ciclosporina/farmacologia , Nifedipino/farmacologia , Óxido Nítrico Sintase/efeitos dos fármacos , Óxido Nítrico Sintase/genética , RNA Mensageiro/efeitos dos fármacos , Animais , Peso Corporal/efeitos dos fármacos , Ciclosporina/toxicidade , Taxa de Filtração Glomerular/efeitos dos fármacos , Gliceraldeído-3-Fosfato Desidrogenases/metabolismo , Isoenzimas/genética , Isoenzimas/metabolismo , Córtex Renal/efeitos dos fármacos , Córtex Renal/enzimologia , Medula Renal/efeitos dos fármacos , Medula Renal/enzimologia , Fígado/efeitos dos fármacos , Fígado/enzimologia , Testes de Função Hepática , Masculino , Nefrectomia , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico Sintase Tipo I , Óxido Nítrico Sintase Tipo II , Óxido Nítrico Sintase Tipo III , Especificidade de Órgãos , RNA Mensageiro/metabolismo , Ratos , Ratos WistarRESUMO
Existe extensa evidencia de que el riñón participa en forma importante en la generación y mantenimiento de la hipertensión arterial. Esta evidencia proviene de modelos animales experimentales, de cepas de ratas con hipertensión genética y de estudios en humanos. Todos los genes identificados hasta la fecha en los que mutaciones puntuales producen alteraciones crónicas en la presión arterial, codifican para proteínas que participan en una vía común que tiene, con fin la reabsorción renal de sodio. La natriuresis de presión constituye el mecanismo de enlace entre la presión arterial y la excreción urinaria de sodio; en los últimos años hemos empleado a entender cómo se da la conexión entre presión arterial y natriuresis ya que se ha reconocido, la importancia de la presión del intersticio renal en este fenómeno. Parte del nuevo entendimiento de la fisiología de la excreción urinaria de sodio se debe al desarrollo de nuevas estrategias como la videomicroscopía y flujometría doppler-laser que permiten medir, con alto grado de certeza, los flujos sanguíneos de corteza y médula renales en forma independiente que, en combinación con estrategias ya conocidas como la implantación de cápsulas para determinación de la presión intersticial renal, muestran que la presión del intersticio renal es la responsable de la conexión entre la presión arterial sistémica y la natriuresis y por tanto, modula la presión arterial a largo plazo