開心術前後のtrypsin，thermolysin処理による血中不活性型レニン値の評価

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

　不活性型レニンは活性型レニンの前駆体であることが知られ，そのアミノ酸1次構造もcDNA解析の手法により明らかにされた^1,2）。しかし，循環血液中に活性型レニンの数倍量も存在することの生理学的意義やin vivoでの活性型への転換のメカニズムなど，なお不明な点が多い。今回我々は，開心術後の高レニン・アルドステロン血症と，不活性型レニンの活性化との関連を調べる目的で，trypsinとbacterial enzymeであるthermolysinにより心疾患患者の開心術前後の血中不活性型レニンを活性化し，体外循環の活性化への影響と，両酵素による活性化の相違について若干の知見を得たので報告する。

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 untill 60 min at 0~37℃ 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.