RESUMEN
The goal of the present research was to elucidate the roles and mechanisms by which the sensory nervous system, through the actions of potent vasodilator neuropeptides, regulates cardiovascular function in both the normal state and in the pathophysiology of hypertension. The animal models of acquired hypertension studied were deoxycorticosterone-salt (DOC-salt), subtotal nephrectomy-salt (SN-salt), and Nomega-nitro-L-arginine methyl ester (L-NAME)-induced hypertension during pregnancy in rats. The genetic model was the spontaneously hypertensive rat (SHR). Calcitonin gene-related peptide (CGRP) and substance P (SP) are potent vasodilating neuropeptides. In the acquired models of hypertension, CGRP and SP play compensatory roles to buffer the blood pressure (BP) increase. Their synthesis and release are increased in the DOC-salt model but not in the SN-salt model. This suggests that the mechanism by which both models lower BP in SN-salt rats is by increased vascular sensitivity. CGRP functions in a similar manner in the L-NAME model. In the SHR, synthesis of CGRP and SP is decreased. This could contribute to the BP elevation in this model. The CGRP gene knockout mouse has increased baseline mean arterial pressure. The long-term synthesis and release of CGRP is increased by nerve growth factor, bradykinin, and prostaglandins and is decreased by alpha2-adrenoreceptor agonists and glucocorticoids. In several animal models, sensory nervous system vasoactive peptides play a role in chronic BP elevation. In the acquired models, they play a compensatory role. In the genetic model, their decreased levels may contribute to the elevated BP. The roles of CGRP and SP in human hypertension are yet to be clarified.
Asunto(s)
Péptido Relacionado con Gen de Calcitonina/fisiología , Hipertensión/fisiopatología , Neuronas Aferentes/metabolismo , Células Receptoras Sensoriales/metabolismo , Sustancia P/fisiología , Animales , Presión Sanguínea/efectos de los fármacos , Péptido Relacionado con Gen de Calcitonina/farmacología , Células Cultivadas , Desoxicorticosterona , Modelos Animales de Enfermedad , Femenino , Hipertensión/inducido químicamente , Ratones , Ratones Noqueados , NG-Nitroarginina Metil Éster , Embarazo , Ratas , Ratas Endogámicas SHR , Sustancia P/farmacologíaRESUMEN
The goal of the present research was to elucidate the roles and mechanisms by which the sensory nervous system, through the actions of potent vasodilator neuropeptides, regulates cardiovascular function in both the normal state and in the pathophysiology of hypertension. The animal models of acquired hypertension studied were deoxycorticosterone-salt (DOC-salt), subtotal nephrectomy-salt (SN-salt), and Nomega-nitro-L-arginine methyl ester (L-NAME)-induced hypertension during pregnancy in rats. The genetic model was the spontaneously hypertensive rat (SHR). Calcitonin gene-related peptide (CGRP) and substance P (SP) are potent vasodilating neuropeptides. In the acquired models of hypertension, CGRP and SP play compensatory roles to buffer the blood pressure (BP) increase. Their synthesis and release are increased in the DOC-salt model but not in the SN-salt model. This suggests that the mechanism by which both models lower BP in SN-salt rats is by increased vascular sensitivity. CGRP functions in a similar manner in the L-NAME model. In the SHR, synthesis of CGRP and SP is decreased. This could contribute to the BP elevation in this model. The CGRP gene knockout mouse has increased baseline mean arterial pressure. The long-term synthesis and release of CGRP is increased by nerve growth factor, bradykinin, and prostaglandins and is decreased by alpha2-adrenoreceptor agonists and glucocorticoids. In several animal models, sensory nervous system vasoactive peptides play a role in chronic BP elevation. In the acquired models, they play a compensatory role. In the genetic model, their decreased levels may contribute to the elevated BP. The roles of CGRP and SP in human hypertension are yet to be clarified
Asunto(s)
Animales , Femenino , Embarazo , Ratones , Ratas , Péptido Relacionado con Gen de Calcitonina , Hipertensión , Sustancia P , Presión Sanguínea , Péptido Relacionado con Gen de Calcitonina , Desoxicorticosterona , Modelos Animales de Enfermedad , Hipertensión , NG-Nitroarginina Metil Éster , Sustancia PRESUMEN
The purpose of this multicenter investigation was to determine the efficacy and safety of the alpha/beta-blocker labetalol versus the beta 1-selective beta-blocker atenolol in white and black patients with essential hypertension. Equal numbers of black and white patients were enlisted to form four treatment groups (white patients taking either labetalol or atenolol and black patients taking either labetalol or atenolol). Two hundred ninety-two patients (152 white and 140 black patients) with essential hypertension characterized by a standing diastolic blood pressure of 105 to 119 mm Hg (inclusive) were recruited for this trial. Patients were randomized to either labetalol (dosage titrated from 200 to 1600 mg/day) or atenolol (dosage titrated from 50 to 100 mg/day). The therapeutic goal was achievement of a standing diastolic blood pressure of 90 mm Hg or less or a fall of 15 mm Hg in diastolic pressure from baseline value at the end of the placebo run in period. At the end of the study there were no significant differences in blood pressure or heart rate changes in the supine position between the labetalol and atenolol groups. In contrast, labetalol produced greater reduction in both the standing systolic and diastolic blood pressure (-12/-13 mm Hg, respectively) compared with atenolol (-7/-9 mm Hg; p less than 0.05; p less than 0.005, respectively). The greatest decrease in blood pressure was observed in white patients receiving labetalol. In black patients the decrease in blood pressure was greater in those treated with labetalol compared with atenolol, particularly with respect to the systolic blood pressure. We conclude that the alpha 1-blocking property of labetalol provides an additional lowering of the blood pressure over that seen with beta 1-blockade alone, especially in the standing position, and this enhanced efficacy is not confined to one radical group.