RESUMEN
It remains unknown whether the extent of vasoactive response to exogenous calcitonin gene-related peptide (CGRP) varies among different regional vascular beds. It is also unclear whether endogenous CGRP plays a functional role in regulating basal vascular activity. To address these two issues, experiments were conducted in 27 anesthetized rats instrumented with a carotid flow probe and catheters in a jugular vein, left ventricle (LV), and femoral artery, and in 6 conscious dogs, chronically instrumented with LV pressure gauge, aortic and atrial catheters, and ascending aortic, coronary, carotid, and renal flow probes. In both species, administration of human alpha-CGRP (0.1-0.5 microg/kg, i.v.) induced a dose-dependent peripheral vasodilation that was completely abolished by pretreatment with alpha-CGRP[8-37] (30 microg/kg/min, i.v.), a competitive antagonist of CGRP receptors. Regional blood flow measured by the radioactive microsphere technique in rats showed that the alpha-CGRP (0.3 microg/kg, i.v.)-induced increase in blood flow was greater (p < 0.05) in the heart (+53 +/- 16%) than in the brain (+14 +/- 6%). In the presence of beta-adrenergic receptor blockade with propranolol, however, the increases in blood flow in these two vascular beds were identical. In conscious dogs, alpha-CGRP (0.3 microg/kg, i.v.) produced similar increases in coronary (+24 +/- 6%), carotid (+26 +/- 3%), and renal (+26 +/- 6%) blood flow, which were different from the patterns induced by other vasodilators; at an equivalent level of reduction in mean arterial pressure and total peripheral resistance, alpha-CGRP increased coronary and carotid blood flow significantly less (p < 0.05) than adenosine or nitroprusside. Unlike alpha-CGRP, adenosine and nitroprusside, as expected, induced pronounced differential blood flow changes in these vascular beds. Neither systemic hemodynamics nor regional blood flow distribution was altered by the administration of a pharmacological blocking dose of alpha-CGRP[8-37] in the two species. Thus, we conclude that endogenous alpha-CGRP does not play an important role in cardiovascular regulation under normal, resting conditions, although exogenous alpha-CGRP induces a marked, comparable vasorelaxation in different regional vascular beds.
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Péptido Relacionado con Gen de Calcitonina/farmacología , Hemodinámica/efectos de los fármacos , Adenosina/farmacología , Animales , Presión Sanguínea/efectos de los fármacos , Arterias Carótidas/efectos de los fármacos , Perros , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Masculino , Nitroprusiato/farmacología , Ratas , Ratas Sprague-Dawley , Flujo Sanguíneo Regional/efectos de los fármacos , Especificidad de la Especie , Vasodilatadores/farmacologíaRESUMEN
Many patients believe that the education they receive about their health and their illnesses is inadequate or lacking. Nurse executives are in a key position to influence their patients' abilities to become more informed and to take greater responsibility for their healthcare decisions. In the article, the authors discuss Massachusetts General Hospital's state-of-the-art consumer health information library, including how the project was planned, organized, and implemented.