Glybenclamide Attenuates the Cardiovascular Effects of Iptakalim in Rats

Objective To study the cardiovascular effects of Iptakalim and the influence of the glibenclamide(ATP sensitive potassium channel antagonist) on the cardiovascular action of iptakalim Methods Tail cuff was used to record the systolic blood pressure and heart rate in SHR Blood pressure was recorded by physiologic recorder, and the cardiac function parameters were recorded by SMUP PC software Results In pentobarbital anaesthetized normotensive rats, Iptakalim 0 125～2 0 mg·kg -1 ·iv dose dependently decreased blood pressure, heart rate, LVSP, +dp/dt max ,+dp/dt max /IP,Vmax, dp/dt max and increased dp/dt max time dose dependently Suggesting that Iptakalim inhibits myocardial contractility and diastolic function Pinacidil or Nifedipine at the dose of 1 0 mg·kg -1 iv show analogous effect as well Glibenclamide completely antagonized the antihypertensive and cardiac negative inotropic effects by Iptakalim (0 5 mg·kg -1 ) and pinacidil (1 0 mg·kg -1 ) Iptakalim at high dos of 2 0 mg·kg -1 iv with no effect on nifdipine induced depressive effect on myocardium Conclusion The cardiovascular effects of Iptakalim were different from those of nifedipine, but similar to those of pinacidil The pharmacological properties of Iptakalim appears to be a ATP sensitive potassium channel activators