Mechanisms underlying arginine vasopressin-induced relaxation in monkey isolated coronary arteries.
OBJECTIVE
The present study was undertaken to examine whether arginine vasopressin (AVP) relaxes primate coronary artery and to analyse the mechanisms of its action in reference to endothelial nitric oxide and AVP receptor subtype.


METHODS
Isometrical tension responses to AVP and desmopressin were recorded in isolated monkey coronary arteries.


RESULTS
AVP (10(-9) to 10(-7) mol/l) induced a concentration-related relaxation; endothelium-denudation abolished the response. Treatment with N(G)-nitro-L-arginine, but not the D-enantiomer, abolished the endothelium-dependent relaxation, which was restored by L-arginine. Treatment with SR49059 and [Pmp1,Tyr(Me)2]-Arg8-vasopressin, selective inhibitors of V1 receptor subtype, attenuated the relaxant response to AVP, whereas the relaxation induced by sodium nitroprusside was not affected by SR49059. Desmopressin, a V2 receptor agonist, up to 10(-8) mol/l did not elicit relaxation.


CONCLUSIONS
It is concluded that AVP-induced monkey coronary arterial relaxation is mediated via nitric oxide synthesized from L-arginine in association with stimulation of V1 receptor subtypes in the endothelium.
Department of Pharmacology, Shiga University of Medical Science, Seta, Ohtsu, Japan.
T
T
Okamura
K
K
Ayajiki
H
H
Fujioka
N
N
Toda
D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001127:Arginine Vasopressin / Q000494:pharmacology*; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D008251:Macaca; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D011759:Pyrrolidines / Q000494:pharmacology; D017483:Receptors, Vasopressin / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects*
D007211:Indoles; D011759:Pyrrolidines; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D009569:Nitric Oxide; D001120:Arginine; C082134:relcovaptan; D019331:NG-Nitroarginine Methyl Ester