OPC-21268 antagonizes arginine vasopressin-induced vasoconstrictor response in the spinally-anesthetized dog

We studied the antagonistic actions of OPC-21268 (1-(1-[4-(3-acetylaminopropoxy)-benzoyl]-4-piperidyl)-3,4-dihydro- 2(1H)-quinolinone) on the arginine vasopressin (AVP)-induced vasoconstrictor response in the spinally-anesthetized dog. OPC-21268 at doses of 0.3, 1.0 and 3.0 mg/kg, i.v. produced a rightward parallel shift of the dose-response curves for AVP in a dose-dependent manner. The doses of OPC-21268 were similar to those that inhibited the AVP-induced vasoconstrictor response in the rat. This observation suggests that OPC-21268 acts as a V1-AVP-receptor antagonist in peripheral resistance vessels in dogs as well as in rats.