Tomio Okamura (1), Jian-Xin Zhang (1), Kenji Kangawa (2) and Noboru Toda
(1) Department of Pharmacology, Shiga University of Medical Science, Seta, Ohtsu 520-21, Japan
(2) National Cardiovascular Center Research Institute, Fujishirodai, Suita, Osaka 565, Japan
Abstract: Adrenomedullin (AM) inhibited the pressor action caused by transmural electrical stimulation in perfused isolated canine mesenteric arteries. The inhibitory potency of AM was greater than that of calcitonin gene-related peptide (CGRP) or proadrenomedullin NH2-terminal 20 peptide (PAMP). [8 - 37]CGRP did not affect the inhibitory action of AM, but suppressed the CGRP-induced inhibition. It may be concluded that AM has an ability to inhibit adrenergic neuronal transmission without the mediation of CGRP1 receptors in the peripheral vasculature, and this inhibition partly participates in the potent hypotensive action of AM.
Keywords: Adrenomedullin, Adrenergic neurotransmission, Depressor action