Effect on nitroglycerin and other organic nitrates on the in-vitro biosynthesis of arachidonic acid-metabolites in washed human platelets.

Organic nitrates exert well known vasodilating effects in coronary arteries, although the exact mechanism of action is not fully understood. In this study the influence of these drugs on the biosynthesis of eicosanoids from labelled exogenous arachidonic acid (AA) in isolated platelets was examined. Platelet malondialdehyde (MDA)-formation in the presence of the substances tested in this system was studied too. The vasodilating drugs were found to reduce the conversion rate to TxB2, hydroxy-5,8,10-heptadecatrienoic acid (HHT) and MDA in platelets dose-dependently. Isosorbid-5-mononitrate (ISMN), nitroglycerin (NG) and SIN 1, the active metabolite of molsidomin, showed their inhibitory effects at concentrations of about 1mM, isosorbid-dinitrate (ISDN) had a much weaker effect on platelet-biosynthesis - a concentration of about 3mM was necessary to inhibit TxB2-formation significantly.