Reciprocal interactions among neuropeptides and adenosine in the cardiovascular system of rats: a role of K(ATP) channels.
Possible reciprocal interactions among vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP) and adenosine were investigated in anesthetized rats. Changes in arterial blood pressure were taken as a parameter to evaluate the interactions. The i.v. bolus injections of VIP (0.3 or 1 microg kg(-1)), CGRP (0.1 or 0.3 microg kg(-1)) and adenosine (1-100 microg kg(-1)), like acetylcholine (0.1 microg kg(-1)), produced reductions of blood pressure, accompanied by slight changes (less than 5% except for 100 microg kg(-1) adenosine) in heart rate (HR). The vasodepressor responses to VIP and CGRP were significantly augmented by i.v. infusion of adenosine (3 microg kg(-1) min(-1)). The vasodepressor responses to adenosine and CGRP by VIP (0.03 microg kg(-1) min(-1)), and those to adenosine and VIP by CGRP (1 ng kg(-1) min(-1)) were also enhanced. The response to acetylcholine remained unchanged before and during i.v. infusion of either VIP, CGRP or adenosine. The i.v. infusion of cromakalim (0.1 microg kg(-1) min(-1)) also augmented the responses to VIP, CGRP and adenosine, but not to acetylcholine, whereas a single bolus i.v. injection of glibenclamide (20 mg kg(-1)) significantly attenuated each one of them. The present results suggest that endogenous vasodilators, such as VIP, CGRP and adenosine, reciprocally interact in the body, at least partly through ATP-sensitive K+ channels.
Sakai
K
K
Central Research Laboratories, Chugai Pharmaceutical, Tokyo, Japan.
Saito
K
K
D000109:Acetylcholine / Q000494:pharmacology; D000241:Adenosine / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000502:physiology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology; D002319:Cardiovascular System / Q000187:drug effects* / Q000294:innervation / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D009479:Neuropeptides / Q000494:pharmacology*; D015221:Potassium Channels / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
D009479:Neuropeptides; D015221:Potassium Channels; D014660:Vasoactive Intestinal Peptide; D000255:Adenosine Triphosphate; D015740:Calcitonin Gene-Related Peptide; D000241:Adenosine; D000109:Acetylcholine