Abstract
We examined the effect of Cilostazol, a cyclic AMP phosphodiesterase inhibitor, rat isolated pulmonary arterial ring tone.
Cilostazol dilated pulmonary arterial rings pre-contracted with 10-6M phenylephrine in a dose-dependent manner (ED50 3.00×10-6M). This vasodilatory effect of Cilostazol was not affected by pretreatment with meclofenamate (10-5M), mechanical endothelium denudation, methylene blue (10-5M) or nitro-L-arginine (2×10-4M). The vasodilatory effect of Cilostazol on rat thoracic aortic rings was stronger than that on rat pulmonary arterial ring (ED50 1.89×10-6M). Cilostazol (10-6M-10-4M) inhibited hypoxic contraction of rat pulmonary rings in a dose-dependent manner. Our experimental data indicated that Cilostazol caused vasodilation regardless of vascular endothelium function and inhibited hypoxic contraction due to inhibition of cyclic AMP phosphodiesterase.
