ZAPRINAST, CICLETANINE, AND VERAPAMIL ATTENUATE OVERDRIVE PACING-INDUCED MYOCARDIAL-ISCHEMIA IN CONSCIOUS RABBITS

In conscious rabbits equipped with right ventricular electrode and lef t ventricular polyethylene catheters, zaprinast and cicletanine, inhib itors of phosphodiesterase (PDE) V and PDEs I and V, respectively, as well as verapamil, a Ca2+ channel blocker, decreased intracavital ST-s egment elevation induced by ventricular overdrive pacing (VOP). Zaprin ast and cicletanine attenuated VOP-induced QT reduction and increase i n left ventricular end-diastolic pressure (LVEDP), whereas verapamil i ncreased LVEDP. These results suggest that inhibition of cGMP-PDEs can protect heart against ischemia.