Endothelium-dependent relaxations to histamine in the rat common carotid, renal and cranial mesenteric artery

AbstractThe effect of histamine on the isolated rat common carotid, renal and cranial mesenteric arteries was examined. Histamine (10−8 – 10−4 m) caused concentration-dependent relaxations of the arteries during contractions induced with phenylephrine (10−8 – 10−7 m). Removal of the vascular endothelium inhibited the histamine-induced relaxations. Pyrilamine (6 × 10−6 m), but not metiamide (10−6 m), abolished the relaxant effect of histamine. Moreover, pyrilamine (6 × 10−6 m) did not affect endothelium-dependent relaxations of the arteries produced with acetylcholine. These results indicate that histamine causes endothelium-dependent relaxations of the rat peripheral large conduit arteries, which appeared to be mediated via H1-histaminergic receptors.