Triamterene and mouse liver tryptophan pyrrolase: possible activation of cytosol by the pteridine in enhancing enzymic activity.

Triamterene (2,4,7-triamino-6-phenylpteridine), a diuretic drug, affects the hepatic endogenous holotryptophan pyrrolase (EC 1.13.1.12) in the mouse, with stress from sham-operation as a preconditioning factor; under these conditions, maximum levels of enzymatic activities are obtained. These values range from 6.87 to 9.84 units with a mean value of 8.252 mumoles of kynurenine per gram tissue per hour. Employing similar experimental designs, the effects of cortisol were studied for comparative evaluation; these activities range from 4.154 to 4.999 units with a mean value of 4.49. The significance and the possible mechanism of action of triamterene are discussed.