Effects of 2-Nicotinamidethyl Nitrate (SG-75), a New Antianginal Drug, on the Cyclic AMP Phosphodiesterase Activity

Abstract

The effect of a potent coronary vasodilator, SG-75, on the purified cyclic AMP phosphodiesterase of the bovine heart was compared with that of papaverine. SG-75 inhibited the phosphodiesterase activity in a competitive manner, the IC₅₀ being 10 mM. SG-75 was approximately 300 times less potent than papaverine in inhibiting the phosphodiesterase activity. Thus, it is unlikely that the phosphodiesterase inhibition by SG-75 is involved in its vasodilator action.