In vitro study of the relaxant effect of doxazosin in the activity of smooth muscles in isolated goat renal artery

Abstract

Doxazosin is a competitive, short-acting, selective alpha 1-adrenoceptor antagonist. Selective alpha 1-blockers dilate blood vessels in the veins and arteries. The specificity for alpha-adrenoreceptors causes the smooth muscle of the blood vessels to relax. The findings of the recording and analysis demonstrate that doxazosin generates an endothelium-dependent relaxation of renal artery rings that had been pre-contracted with a high amount of KCl (60 mM) or phenylephrine (PE) (10-5 M). Additionally, doxazosin shows strong inhibitory effects on PE and weaker effects on contractions induced by KCl. Pre-incubating renal artery rings with 4-aminopyridine (4-AP), indomethacin, potassium (K+) channels blocker (TEA), barium chloride (BaCl2), prostaglandin I2 (PGI2) inhibitor (Indomethacin), and nitric oxide (NO) synthase inhibitor (L-Name), significantly affects the relaxation brought on by doxazosin. Contrarily, neither glibenclamide (GLIB) nor clotrimazole, show any effect on the relaxation caused by doxazosin. Doxazosin’s role suggests that a Ca++ channel-blocking mechanism has a relaxing impact on the smooth muscles of the renal artery. The relaxing effect of doxazosin is thus concluded from these findings to involve both potassium and calcium channels, potentially through the blockage of KV, KCa, KIr, endothelium/NO, PGI2, and voltage-dependent calcium channels.