Jpn. J. Pharmacol. 81 (3), 309 - 312 (1999)

On the Inotropic Actions of Arginine Vasopressin in Ventricular
Muscle of the Guinea Pig Heart

Susumu Fujisawa and Toshihiko Iijima*

Department of Pharmacology, Akita University School of Medicine, Akita 010 - 8543, Japan
(*) To whom correspondence should be addressed.

Abstract: Arginine vasopressin (AVP) (0.03 - 3 ƒÊM) produced transient negative responses that were followed by slowly developing positive inotropic responses in guinea pig papillary muscles. The inotropic responses were antagonized by OPC-21268 (10 ƒÊM), but not by OPC-31260, and suppressed by neomycin (3 mM). The negative inotropic response was hardly affected by staurosporine (10 nM) and H-7 (10 ƒÊM). AVP (1 ƒÊM) elicited a transient decrease followed by a slowly developing increase in ICa. The latter increase in ICa was not elicited in the presence of staurosporine (1 nM). These results indicate that AVP stimulates V1 receptors that couple to phosphoinositide hydrolysis and thereby increases intracellular Ca2+ and activates protein kinase C.

Keywords: Vasopressin-1 receptor, Protein kinase C, L-type Ca2+ current

Copyright© The Japanese Pharmacological Society 1999

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