Influence of the endothelium on tone and the response of isolated pig coronary artery to norepinephrine.

摘要: The influence of the endothelium on smooth muscle tone and response pig right coronary artery to norepinephrine (NE) was studied. Isolated rings with without were stretched in presence nitroprusside a tension previously determined be optimal for contraction. During wash out nitroprusside, spontaneously generated representing 24% contraction caused by potassium (120 mM); no significant spontaneous observed. Relaxations NE contracted prostaglandin F2 alpha (PGF2 alpha). In endothelium, relaxed as well that produced PGF2 alpha. Independent mode or degree contraction, more sensitive than endothelium. difference sensitivity between likely due endothelial cell alpha-2 adrenoceptors, inasmuch abolished rauwolscine. propranolol prazosin, endothelium-dependent relaxations observed which also inhibited Nevertheless, beta adrenoceptors are predominant mediator relaxation muscle, because greater shift induced compared removal. Accordingly, under resting conditions, contractions only propranolol. These attenuated prazosin rauwolscine, but blocked combination both adrenoceptor antagonists.(ABSTRACT TRUNCATED AT 250 WORDS)