[Assessment of plasma inactive renin by trypsin and thermolysin treatment during open heart surgery].

Plasma inactive renin (IRA) were assayed through open heart surgery by trypsin treatment in twenty-two patients. Postoperatively plasma renin activities and IRA increased, remarkably in IRA, however total renin activities were lesser than plasma renin activities during extracorporeal circulation. From the results of addition of 125I-angiotensin I before trypsin treatment, the presence of unknown enzyme was assumed, which was activated by trypsin and catalyzed angiotensin I in extracorporeal circulation. Bacterial enzyme, thermolysin, also activated plasma inactive renin, more stably until 60 min at 0-37 degrees C than trypsin. By trypsin, activities were in peaks at 1 min and gradually decreased thereafter. Conclusively we could assess the superiority of thermolysin treatment over trypsin treatment.