RESUMEN
Posttraumatic stress disorder (PTSD) was previously thought to be a psychological reaction precipitated by exposure to war, sexual and physical violence; however, PTSD is also prevalent after life-threatening medical events, such as stroke and myocardial infarction. After such events PTSD is often underdiagnosed despite the fact that it is clearly associated with adverse clinical outcomes including recurrence of cardiac events and increased mortality. Moreover, PTSD increases the risk of vascular events. This review summarizes the bidirectional relationship between PTSD and vascular diseases and outlines current knowledge regarding clinical features, prevalence and the putative underlying pathophysiological mechanisms.
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Modelos Cardiovasculares , Trastornos por Estrés Postraumático/mortalidad , Trastornos por Estrés Postraumático/fisiopatología , Enfermedades Vasculares/mortalidad , Enfermedades Vasculares/fisiopatología , Causalidad , Comorbilidad , Medicina Basada en la Evidencia , Humanos , Prevalencia , Trastornos por Estrés Postraumático/psicología , Tasa de Supervivencia , Enfermedades Vasculares/psicologíaRESUMEN
At least one-third of stroke survivors suffer from depression. The development of comorbid depression after stroke is clinically highly significant because post-stroke depression is associated with increased mortality, slows recovery and leads to worse functional outcomes. Here, we review the evidence that post-stroke depression can be effectively modelled in experimental rodents via a variety of approaches. This opens an exciting new window onto the neurobiology of depression and permits probing potential underlying mechanisms such as disturbed cellular plasticity, neuroendocrine dysregulation, neuroinflammation, and neurodegeneration in a novel context. From the point of view of translational stroke research, extending the scope of experimental investigations beyond the study of short-term end points and, in particular, acute lesion size, may help improve the relevance of preclinical results to human disease. Furthermore, accumulating evidence from both clinical and experimental studies offers the tantalizing prospect of 5-hydroxytryptaminergic antidepressants as the first pharmacological therapy for stroke that would be available during the subacute and chronic phases of recovery. Interdisciplinary neuropsychiatric research will be called on to dissect the mechanisms underpinning the beneficial effects of antidepressants on stroke recovery.
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Depresión , Modelos Animales de Enfermedad , Accidente Cerebrovascular , Animales , Antidepresivos/uso terapéutico , Encéfalo/fisiología , Depresión/tratamiento farmacológico , Depresión/patología , Depresión/fisiopatología , Depresión/psicología , Humanos , Ratones , Degeneración Nerviosa , Estrés Psicológico , Accidente Cerebrovascular/patología , Accidente Cerebrovascular/fisiopatología , Accidente Cerebrovascular/psicologíaRESUMEN
Folate deficiency has been linked to neurodegenerative and stress-related diseases such as stroke, dementia and depression. The role of the neurotrophins nerve growth factor (NGF) and neurotrophin-3 (NT-3) in stress-related disorders and neurodegeneration has garnered increasing attention in recent years. Uracil misincorporation is involved in the neuropsychiatric dysfunction induced by experimental folate deprivation. However, the effects of folate deficiency on the expression of NGF and NT-3 in brain tissue have not yet been investigated. In a 2×2 design, aged mice lacking uracil-DNA N-glycosylase (Ung(-/-)) versus wild-type (Ung(+/+)) controls were subjected to a folate-deficient diet versus a regular diet for three months. Independent of genotype, folate deficiency led to decreased NGF protein levels in the frontal cortex and amygdala. In the hippocampus, NGF levels were increased in UNG(-/-) mice on the normal diet, but not under folate deficiency, while in UNG(+/+) mice, folate deprivation did not affect hippocampal NGF content. NT-3 protein concentrations were neither affected by genotype nor by folate deficiency. Altogether, the results of our study show that folate deficiency affects NGF levels in the frontal cortex, amygdala and hippocampus. The decrease in NGF content in the hippocampus in response to folate deficiency in Ung(-/-) mice may contribute to their phenotype of enhanced anxiety and despair-like behavior as well as to selective hippocampal neurodegeneration.
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Amígdala del Cerebelo/metabolismo , Deficiencia de Ácido Fólico/metabolismo , Lóbulo Frontal/metabolismo , Hipocampo/metabolismo , Factor de Crecimiento Nervioso/metabolismo , Estrés Psicológico/metabolismo , Animales , Deficiencia de Ácido Fólico/genética , Deficiencia de Ácido Fólico/psicología , Genotipo , Ratones , Ratones Noqueados , Factor de Crecimiento Nervioso/antagonistas & inhibidores , Factor de Crecimiento Nervioso/genética , Estrés Psicológico/genética , Estrés Psicológico/psicologíaRESUMEN
STUDY DESIGN: Group comparison and cross-sectional study. OBJECTIVES: To replicate previous findings regarding electroencephalographic (EEG) pattern differences in a larger sample of patients with spinal cord injury (SCI) and chronic pain than previously studied, and examine associations between pain severity and EEG activity in a sample of patients with SCI and chronic pain. SETTING: USA. METHODS: EEG data were collected in an eyes-closed condition from 38 individuals with SCI and chronic pain, 16 individuals with SCI who did not have chronic pain and 28 healthy controls. Pain intensity experienced during the EEG assessment was assessed in the chronic pain group. Absolute and relative power in four frequency bands (delta, theta, alpha, and beta) were compared between the groups, and correlation coefficients between bandwidth activity and pain intensity in the pain group were computed. RESULTS: Previously identified activity pattern differences (that is, more theta and less alpha) in those with SCI and chronic pain versus individuals with SCI and no pain and healthy controls were largely replicated. However, few significant associations between pain severity and EEG activity measures activity were found, and those that were found (more alpha activity associated with more pain as measured from frontal electrode sites) was in a direction opposite than predicted. CONCLUSION: The findings indicate that certain EEG activity patterns may be associated with more pain or a vulnerability to experience chronic pain in persons with SCI. Research examining the extent to which changes in this EEG activity may result in pain relief is warranted.
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Encéfalo/fisiopatología , Dolor Crónico/etiología , Dolor Crónico/fisiopatología , Electroencefalografía , Traumatismos de la Médula Espinal/complicaciones , Traumatismos de la Médula Espinal/fisiopatología , Adulto , Anciano , Anciano de 80 o más Años , Análisis de Varianza , Estudios Transversales , Interpretación Estadística de Datos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neuralgia/etiología , Neuralgia/fisiopatología , Dimensión del DolorRESUMEN
Blood flow imaging is an important tool in cerebrovascular research. Mice are of special interest because of the potential of genetic engineering. Magnetic resonance imaging (MRI) provides three-dimensional noninvasive quantitative methods of cerebral blood flow (CBF) imaging, but these MRI techniques have not yet been validated for mice. The authors compared CBF imaging using flow sensitive alternating inversion recovery (FAIR)-MRI and (14)C-Iodoantipyrine (IAP)-autoradiography in a mouse model of acute stroke. Twenty-nine male 129S6/SvEv mice were subjected to filamentous left middle cerebral artery occlusion (MCAo). CBF imaging was performed with (14)C-IAP autoradiography and FAIR-MRI using two different anesthesia protocols, namely intravenous infusion of etomidate or inhalation of isoflurane, which differentially affect perfusion. Using (14)C-IAP autoradiography, the average CBF in ml/(100 g*min) was 160+/-34 (isoflurane, n=5) vs. and 59+/-21 (etomidate, n=7) in the intact hemisphere and 43+/-12 (isoflurane, n=5) vs. 36+/-12 (etomidate, n=7) in the MCAo hemisphere. Using FAIR-MRI, the corresponding average CBFs were 208+/-56 (isoflurane, intact hemisphere, n=7), 84+/-9 (etomidate, intact hemisphere, n=7), 72+/-22 (isoflurane, MCAo hemisphere, n=7) and 48+/-13 (etomidate, MCAo hemisphere, n=7). Regression analysis showed a strong linear correlation between CBF measured with FAIR-MRI and (14)C-IAP autoradiography, and FAIR-MRI overestimated CBF compared to autoradiography. FAIR-MRI provides repetitive quantitative measurements of hemispheric CBF in a mouse model of stroke.
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Circulación Cerebrovascular/fisiología , Imagen por Resonancia Magnética , Accidente Cerebrovascular/patología , Accidente Cerebrovascular/fisiopatología , Anestésicos/administración & dosificación , Animales , Antiinflamatorios no Esteroideos/farmacocinética , Antipirina/análogos & derivados , Antipirina/farmacocinética , Autorradiografía/métodos , Tiempo de Circulación Sanguínea/efectos de los fármacos , Mapeo Encefálico , Isótopos de Carbono/farmacocinética , Circulación Cerebrovascular/efectos de los fármacos , Modelos Animales de Enfermedad , Etomidato/administración & dosificación , Imagenología Tridimensional , Isoflurano/administración & dosificación , Modelos Lineales , Masculino , RatonesAsunto(s)
Anticolesterolemiantes/efectos adversos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/efectos adversos , Enfermedades Musculares/inducido químicamente , Enfermedades Musculares/diagnóstico , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Guías de Práctica Clínica como Asunto , Pautas de la Práctica en Medicina , Resultado del TratamientoRESUMEN
Binding of sterol response element binding protein 1a to sterol response element-1 (SRE-1) in the promoter region of lanosterol 14 alpha-demethylase (14DM) has been demonstrated previously. Decreased 14DM activity has been shown to result in accumulation of the intermediate, 3 beta-hydroxy-lanost-8-en-32-al, a known translational downregulator of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase. Since it has also been demonstrated that feedback regulation of hepatic HMG-CoA reductase occurs primarily at the level of translation, the effects of dietary cholesterol and cholesterol lowering agents on levels of hepatic 14DM mRNA and immunoreactive protein were investigated. Addition of 1% cholesterol to a chow diet markedly decreased hepatic 14DM mRNA and protein levels in Sprague-Dawley rats. The extent and time course of this decrease in 14DM immunoreactive protein closely paralleled that of HMG-CoA reductase. Supplementation of the diet with the HMG-CoA reductase inhibitor, Lovastatin, to a level of 0.02%, raised 14DM mRNA and protein levels 2- to 3-fold. Addition of 2% Colestipol, a bile acid binding resin, to the chow diet caused smaller increases. The highest level of 14DM protein expression was observed in liver, the major site of feedback regulation of HMG-CoA reductase by cholesterol. Taken together, these observations suggest a critical role for 14DM in the feedback regulation of hepatic HMG-CoA reductase.
Asunto(s)
Anticolesterolemiantes/farmacología , Colesterol/metabolismo , Sistema Enzimático del Citocromo P-450/biosíntesis , Sistema Enzimático del Citocromo P-450/química , Regulación Enzimológica de la Expresión Génica , Hígado/enzimología , Oxidorreductasas/biosíntesis , Oxidorreductasas/química , Animales , Western Blotting , Colestipol/farmacología , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/farmacología , Immunoblotting , Lovastatina/farmacología , Masculino , Modelos Biológicos , Biosíntesis de Proteínas , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Esterol 14-Desmetilasa , Factores de Tiempo , Distribución TisularRESUMEN
After mild ischemic insults, many neurons undergo delayed neuronal death. Aberrant activation of the cell cycle machinery is thought to contribute to apoptosis in various conditions including ischemia. We demonstrate that loss of endogenous cyclin-dependent kinase (Cdk) inhibitor p16(INK4a) is an early and reliable indicator of delayed neuronal death in striatal neurons after mild cerebral ischemia in vivo. Loss of p27(Kip1), another Cdk inhibitor, precedes cell death in neocortical neurons subjected to oxygen-glucose deprivation in vitro. The loss of Cdk inhibitors is followed by upregulation of cyclin D1, activation of Cdk2, and subsequent cytoskeletal disintegration. Most neurons undergo cell death before entering S-phase, albeit a small number ( approximately 1%) do progress to the S-phase before their death. Treatment with Cdk inhibitors significantly reduces cell death in vitro. These results show that alteration of cell cycle regulatory mechanisms is a prelude to delayed neuronal death in focal cerebral ischemia and that pharmacological interventions aimed at neuroprotection may be usefully directed at cell cycle regulatory mechanisms.
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Isquemia Encefálica/metabolismo , Quinasas CDC2-CDC28 , Proteínas de Ciclo Celular , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Quinasas Ciclina-Dependientes/antagonistas & inhibidores , Proteínas Asociadas a Microtúbulos/metabolismo , Neuronas/metabolismo , Proteínas Proto-Oncogénicas , Proteínas Supresoras de Tumor , Animales , Isquemia Encefálica/patología , Bromodesoxiuridina , Ciclo Celular/fisiología , Muerte Celular , Hipoxia de la Célula , Células Cultivadas , Ciclina D1/metabolismo , Quinasa 2 Dependiente de la Ciclina , Quinasa 4 Dependiente de la Ciclina , Inhibidor p16 de la Quinasa Dependiente de Ciclina/deficiencia , Inhibidor p27 de las Quinasas Dependientes de la Ciclina , Quinasas Ciclina-Dependientes/metabolismo , Modelos Animales de Enfermedad , Inhibidores Enzimáticos/farmacología , Glucosa/deficiencia , Glucosa/metabolismo , Etiquetado Corte-Fin in Situ , Cinetina , Ratones , Ratones Endogámicos , Proteínas Asociadas a Microtúbulos/deficiencia , Neuronas/patología , Oxígeno/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Purinas/farmacología , Ratas , Ratas WistarRESUMEN
Focal cerebral ischemia activates the nuclear protein poly(ADP-ribose) polymerase (PARP) by single DNA strand breaks which leads to energy depletion and cell necrosis. Deletion or inhibition of PARP protects against ischemic brain injury. Here we examined the neuroprotective effect of PJ34, a novel potent inhibitor of PARP in vitro and in vivo. Serum-free primary neuronal cultures derived from rat cortex (E15-17) and kept in culture for 10 days were exposed to oxygen glucose deprivation (OGD) in vitro. Neuronal injury was quantified by LDH release after 24 h. Pretreatment with 30-1000 nM PJ34 significantly protected from OGD-induced cell injury in a dose-dependent manner. For in vivo experiments SV/129 mice were treated with PJ34 (50 microg) by intraperitoneal injection 2 h before 1 h middle cerebral artery occlusion (MCAo) and again 6 h later. Twenty-three h after reperfusion ischemic injury was significantly decreased compared to vehicle-treated controls (infarct volume reduction of 40%, p<0.05). Similarly, in a rat model of MCAo (2 h occlusion followed by up to 22 h reperfusion), PJ34 administration (10 mg/kg i.v.) significantly reduced infarct size, and the effect of the drug was maintained even if it was given as late as 10 min prior to reperfusion time. PJ34 significantly protected in a 4 h, but not in a 24 h permanent occlusion model. In conclusion, PJ34, a novel, potent inhibitor of PARP exerts massive neuroprotective agents, with a significant therapeutic window of opportunity. The present work strengthens the concept that pharmacological PARP inhibition may be a suitable approach for the treatment of acute stroke in man.
Asunto(s)
Isquemia Encefálica/tratamiento farmacológico , Neuronas/efectos de los fármacos , Fármacos Neuroprotectores/uso terapéutico , Fenantrenos/uso terapéutico , Inhibidores de Poli(ADP-Ribosa) Polimerasas , Accidente Cerebrovascular/tratamiento farmacológico , Animales , Encéfalo/patología , Isquemia Encefálica/patología , Células Cultivadas , Medio de Cultivo Libre de Suero , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/uso terapéutico , Infarto de la Arteria Cerebral Media , Ratones , Neuronas/citología , Neuronas/fisiología , Poli(ADP-Ribosa) Polimerasas/metabolismo , Ratas , Ratas Wistar , Accidente Cerebrovascular/patologíaRESUMEN
BACKGROUND AND PURPOSE: Thrombosis superimposed on atherosclerosis causes approximately two thirds of all brain infarctions. We previously demonstrated that statins protect from cerebral ischemia by upregulation of endothelial type III nitric oxide synthase (eNOS), but the downstream mechanisms have not been determined. Therefore, we investigated whether antithrombotic effects contribute to stroke protection by statins. METHODS: 129/SV wild-type and eNOS knockout mice were treated with atorvastatin for 14 days (0.5, 1, and 10 mg/kg). eNOS mRNA from aortas and platelets was measured by reverse-transcriptase polymerase chain reaction. Platelet factor 4 (PF 4) and beta-thromboglobulin (beta-TG) in the plasma were quantified by ELISA. Transient cerebral ischemia was induced by filamentous occlusion of the middle cerebral artery followed by reperfusion. RESULTS: Stroke volume after 1-hour middle cerebral artery occlusion/23-hour reperfusion was significantly reduced by 38% in atorvastatin-treated animals (10 mg/kg) compared with controls. Serum cholesterol levels were not affected by the treatment. eNOS mRNA was significantly upregulated in a dose-dependent manner in aortas and in thrombocytes of statin-treated mice compared with controls. Moreover, indices of platelet activation in vivo, ie, plasma levels of PF 4 and beta-TG, were dose-dependently downregulated in the treatment group. Surprisingly, atorvastatin-treatment did not influence PF 4 and beta-TG levels in eNOS knockout mice. CONCLUSIONS: The synthetic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor atorvastatin upregulates eNOS in thrombocytes, decreases platelet activation in vivo, and protects from cerebral ischemia in normocholesterolemic mice. Antithrombotic and stroke-protective effects of statins are mediated in part by eNOS upregulation. Our results suggest that statins may provide a novel prophylactic treatment strategy independent of serum cholesterol levels.
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Plaquetas/efectos de los fármacos , Isquemia Encefálica/prevención & control , Ácidos Heptanoicos/farmacología , Óxido Nítrico Sintasa/efectos de los fármacos , Activación Plaquetaria/efectos de los fármacos , Pirroles/farmacología , Animales , Aorta/efectos de los fármacos , Aorta/enzimología , Atorvastatina , Coagulación Sanguínea/efectos de los fármacos , Colesterol/sangre , Relación Dosis-Respuesta a Droga , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Infarto de la Arteria Cerebral Media/genética , Ratones , Ratones Noqueados , Óxido Nítrico Sintasa/genética , Óxido Nítrico Sintasa de Tipo II , Óxido Nítrico Sintasa de Tipo III , Factor Plaquetario 4/metabolismo , ARN Mensajero/metabolismo , Daño por Reperfusión/prevención & control , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Regulación hacia Arriba/efectos de los fármacos , beta-Tromboglobulina/metabolismo , Proteínas de Unión al GTP rho/antagonistas & inhibidoresRESUMEN
SV129 or C57BL/6 mice were exposed to hyperbaric oxygenation (HBO, 5 days, 1 h every day, 100% O(2) at 3 atm absolute). One day after the 5th HBO session focal cerebral ischemia was induced. In SV129 mice, HBO induced tolerance against permanent focal cerebral ischemia (n=42, mean infarct volume reduction 27%, P=0.001), but not against transient (30 or 60 min) focal cerebral ischemia. In the C57BL/6 strain of mice, HBO did not induce tolerance against focal cerebral ischemia, even when the duration of ischemia or the HBO protocol were modified. For the first time we demonstrate that HBO can induce tolerance to focal cerebral ischemia, but this effect is strain dependent.
Asunto(s)
Isquemia Encefálica/prevención & control , Isquemia Encefálica/fisiopatología , Oxigenoterapia Hiperbárica , Precondicionamiento Isquémico/métodos , Animales , Infarto Cerebral/patología , Infarto Cerebral/prevención & control , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos , Especificidad de la EspecieRESUMEN
BACKGROUND: Statins improve endothelial function by upregulating endothelial nitric oxide (NO) production that is mediated by inhibiting the isoprenylation of rho GTPase. Withdrawal of statin treatment could suppress endothelial NO production and may impair vascular function. METHODS AND RESULTS: To test this hypothesis, mice were treated for 14 days with 10 mg/kg atorvastatin per day; this led to the upregulation of endothelial NO synthase expression and activity by 2.3- and 3-fold, respectively. Withdrawal of statins resulted in a dramatic, 90% decrease of NO production after 2 days. In mouse aortas and cultured endothelial cells, statins upregulated the expression of rho GTPase in the cytosol, but statins blocked isoprenoid-dependent rho membrane translocation and GTP-binding activity. Inhibiting the downstream targets of rho showed that rho expression is controlled by a negative feedback mechanism mediated by the actin cytoskeleton. Measuring rho mRNA half-life and nuclear run-on assays demonstrated that statins or disruption of actin stress fibers increased rho gene transcription but not rho mRNA stability. Therefore, treatment with statins leads to the accumulation of nonisoprenylated rho in the cytosol. Withdrawing statin treatment restored the availability of isoprenoids and resulted in a massive membrane translocation and activation of rho, causing downregulation of endothelial NO production. CONCLUSIONS: Withdrawal of statin therapy in normocholesterolemic mice results in a transient increase of rho activity, causing a suppression of endothelial NO production. The underlying molecular mechanism is a negative feedback regulation of rho gene transcription mediated by the actin cytoskeleton.
Asunto(s)
Endotelio Vascular/enzimología , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Óxido Nítrico Sintasa/biosíntesis , Proteínas de Unión al GTP rho/metabolismo , Actinas/fisiología , Animales , Transporte Biológico , Northern Blotting , Western Blotting , Bovinos , Membrana Celular/enzimología , Células Cultivadas , Endotelio Vascular/citología , Retroalimentación , Regulación de la Expresión Génica , Ratones , Óxido Nítrico Sintasa de Tipo II , Óxido Nítrico Sintasa de Tipo III , Prenilación de Proteína , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transcripción Genética , Proteínas de Unión al GTP rho/genéticaRESUMEN
Extraction of ER and PgR with 10 mM molybdate in TEDG buffer greatly facilitated their solubilization and a much higher receptor value was observed. However, since molybdate also affects the hormone receptor binding reaction, the apparent receptor activity assayed with molybdate is different from the actual receptor activity normally assayed without molybdate. A correction factor obtained by assaying cytosol with and without adding molybdate can be used to convert the apparent value into the actual value. The mathematical evaluation involving two separate effects of molybdate on receptors is illustrated.
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Molibdeno/farmacología , Receptores de Estrógenos/aislamiento & purificación , Receptores de Progesterona/aislamiento & purificación , Animales , Citosol/análisis , Femenino , Humanos , Matemática , Proteínas/análisis , Conejos , Útero/análisisRESUMEN
Determinants of glomerular ultrafiltration were studied by micropuncture in clamped kidneys of one-kidney Goldblatt rats (n = 10, mean arterial pressure (MAP) = 183 +/- 18 (SD) mm Hg) and in control kidneys of unilateral nephrectomized rats (n = 14, MAP=120 +/- 14 mm Hg). Following saralasin infusion, no significant MAP change occurred in either group. Renal perfusion pressure of clamped kidneys (115 +/- 13 mm Hg) was not different from MAP in controls. Hydrostatic pressure in glomerular capillaries in clamped kidneys was not different from that in controls (60.9 +/- 2.1 vs. 61.7 +/- 3.5 mm Hg). Early proximal flow rate, as a measure for single-nephron GFR, was decreased to 29.5 +/- 1.5 vs. 36.6 +/- 4.4 nl/min in controls (p less than 0.01). Total renal resistance was increased by 102% in the hypertensive group, mainly due to the stenosis (75%) rather than the renal vasculature (27%). Due to a predominant increase of postglomerular vascular resistance, filtration fraction was increased in clamped kidneys (0.37 +/- 0.05 vs. 0.34 +/- 0.06, p less than 0.001). Single nephron glomerular plasma flow was decreased to 158 +/- 23.5 vs. 209 +/- 45.1 nl/min in controls (p less than 0.001). Efferent net ultrafiltration pressure did not differ significantly from zero in either group, i.e. filtration equilibrium was achieved. These results indicate an increased vascular resistance in clamped kidneys, which is caused by a preferential efferent vasoconstriction. This pattern of the vascular bed helps to prevent a further reduction of GFR despite a decrease of blood flow.
Asunto(s)
Hemodinámica , Hipertensión Renovascular/fisiopatología , Nefronas/irrigación sanguínea , Animales , Presión Sanguínea/efectos de los fármacos , Tasa de Filtración Glomerular , Masculino , Nefrectomía , Ratas , Ratas Endogámicas , Circulación Renal , Saralasina/farmacología , Ultrafiltración , Resistencia VascularRESUMEN
Determinants of glomerular ultrafiltration were studied by micropuncture in clamped (n = 11) and unclamped (n = 7) kidneys of two-kidney hypertensive rats and compared to 15 controls. Infusion of the angiotensin II antagonist and saralasin lowered the blood pressure significantly. Glomerular capillary pressure (PGC) in clamped kidneys was decreased to 56 +/- (SD) 3 vs. 61 +/- 3 mm Hg in controls. Early proximal flow rate (EPFR) was decreased to 20 +/- 1 vs. 26 +/- 2 nl/min in controls, at an unchanged single nephron filtration fraction (SNFF), indicating a reduced glomerular plasma flow (SNGPF). Preglomerular resistance (RA) was increased by 21%. In unclamped kidneys PGC was increased to 65 +/- 2 mm Hg. EPFR was increased to 32 +/- 2 nl/min, indicating, at an unchanged SNFF, an increased SNGPF. RA increased by 51%, whereas postglomerular resistance declined by 25%. The ultrafiltration coefficient was reduced by 24% in unclamped kidneys. Our results indicate that in clamped kidneys an increase of RA causes a reduction of PGC and hence a reduction of pressure at the baroreceptor site which may act as a trigger mechanism for renin release.
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Hipertensión/fisiopatología , Obstrucción de la Arteria Renal/fisiopatología , Animales , Modelos Animales de Enfermedad , Tasa de Filtración Glomerular/efectos de los fármacos , Riñón/fisiopatología , Túbulos Renales Proximales/efectos de los fármacos , Túbulos Renales Proximales/fisiopatología , Ratas , Saralasina/farmacologíaAsunto(s)
Angiotensina II/análogos & derivados , Hipertensión Renal/fisiopatología , Nefronas/fisiopatología , Renina/metabolismo , Saralasina/farmacología , Animales , Tasa de Filtración Glomerular/efectos de los fármacos , Hemodinámica/efectos de los fármacos , Presión Hidrostática , Hipertensión Renal/metabolismo , Masculino , Microcirculación , Nefronas/irrigación sanguínea , Ratas , Resistencia VascularRESUMEN
To measure subcapsular pressure of rat kidneys and kidney allografts, microcatheters were implanted in the subcapsular space and the pressure was continuously recorded with a transducer. Subcapsular pressure was found to increase significantly during allograft rejection. After single bolus injection of prednisolone 300 mg/kg on the day of transplantation or on the fourth postoperative day, considerably lower subcapsular pressures were recorded. This steroid effect together with other immunosuppressive measures could have an important influence on graft function and prognosis.
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Edema/tratamiento farmacológico , Trasplante de Riñón , Prednisolona/uso terapéutico , Animales , Rechazo de Injerto/efectos de los fármacos , Masculino , Pronóstico , Ratas , Ratas Endogámicas , Trasplante HomólogoRESUMEN
Intratubular pressures were measured in free flow and after blockade of tubular flow at different distances from the glomerulum in the kidney of Wistar rats. Free flow pressure was ffp = 13.3 +/- 2.5 Torr and stop flow pressure sfp = 41.7 +/- 3.8 Torr. With increasing distance of the blockade from the glomerulum the intratubular pressure decreased being 22.4 +/- 2.1 Torr, when the tubule was blocked at the end of the pars recta. In a second series single nephron filtration rate (gfr) and late proximal flow rates (V) were measured at different intratubular pressures. Free flow gfrf was 26.5 +/- 5.9 nl/min and Vf = 14.7 +/- 4.0 nl/min. The difference of these flow rates divided by tubular length results in a local reabsorption rate of C = 2.9 +/- 0.9 nl/min-mm in the proximal convolution. In the pars recta local reabsorbtion rate was 1.0 +/- 0.3 nl/min-mm. In the proximal convolution C increased with increasing intratubular pressure: deltaC/deltaitp = (2.7 +/- 1.2)-10(-2) nl/min-mm-Torr. Filtration was in disequilibrium in these animals under all conditions examined, hydraulic filtration conductance was K = 1.2 +/- 0.4 nl/min-Torr. Modified methods have been used for intratubular pressure and for flow rate measurements in order to reduce experimental procedure. It is shown, that fractional reabsorption, calculated on the basis of pressure measurements, is a good approximation to results usually obtained by inulin measurements.