[Mechanisms of interaction of acetylsalicylic acid and indomethacin with endoperoxide prostaglandin synthetase].

A study was made of the character and kinetics of interaction of acetylsalicylic acid and indomethacin with endoperoxide prostaglandin synthetase (PGH-synthetase) of sheep vesicular glands and human platelets. Enzymatic activity of PGH-synthetase was determined polarographically with the aid of Clark's electrodes. Acetylsalicylic acid was found to inhibit PGH-synthetase of sheep vesicular glands and human platelets at concentrations of the order of 1 x 10(-6) and 1 x 10(-4) M, whereas indomethacin at concentrations of 1 x 10(-6) and 1 x 10(-7) M, respectively. Acetylsalicylic acid inhibited PGH-synthetase from sheep vesicular glands and that from human platelets at an equal rate. Indomethacin inhibited the enzyme from sheep vesicular glands to a higher degree. Indomethacin reversibly interacted with PGH-synthetase. Meanwhile acetylsalicylic acid inhibited this enzyme irreversibly.