[Mechanism of the vascular action of verapamil and a crown ether derivative]

The effects of verapamil and benzyl-aza-15-crown-5 on pressor reactions of blood pressure and perfusion pressure in the femoral artery after administration of noradrenaline, tyramine, angiotensin amide and stimulation of the femoral nerve were studied in acute experiments on anesthetized cats (pentobarbital sodium, 50 mg/kg). Verapamil (0.5 mg/kg) and benzyl-aza-15-crown-5 (9 mg/kg) suppressed pressor reactions to the nerve stimulation and produced no changes at administration of noradrenaline, tyramine and angiotensin amide. One can suggest that the mechanism of the vasodilating action of verapamil and benzyl-aza-15-crown-5 is due to their inhibitory effect on calcium-dependent release of noradrenaline from terminals of the sympathetic nerves. The search of vasodilating agents in the series of crown-ether derivatives is promising.