Studies on Plasma Angiotensinases in Liver Disease
1968 年 32 巻 8 号 p. 1073-1083
詳細
1968 年 32 巻 8 号 p. 1073-1083
1. Plasma angiotensinase activity was significantly increased in patients with various kinds of liver diseases. The patterns of angiotensinase activity in plasma from normal subjects and patients with liver diseases were compared by horizontal starch block electrophoresis. Angiotensinase activity in normal plasma was found only in the albumin zone, while in plasma from patients with liver diseases it was found not only in the albumin zone but also in the γ-globulin zone. On recovery of the patient, angiotensinase activity in the γ-globulin zone was not demonstrated. This angiotensinase, which was demonstrated electrophoretically in the γ-globulin zone, was named angiotensinase G. 2. On experimental liver damage in rabbits, the findings obtained in human beings were confirmed. 3. Angiotensinase G inactivated both α-asp1-val5-angiotensin II and (α-asp1(NH2)-val5-angiotensin II, but did not inactivate β-asp1 val5-angiotensin II. The optimal pH of the enzyme was between 6.8 and 7.1. The activity of the enzyme was completely inactivated by ethylenediaminetetraacetate treatment and the full activity was restored by addition of manganese. Its activity was inhibited by trasylol as well as diisopropylfluorophosphate. 4. Angiotensinase G could not be detected either in liver extract from normal rabbits or from rabbits with experimental liver damage. When normal rabbit plasma was incubated together with liver extract, angiotensinase G was demonstrated electrophoretically in the incubation mixture. In vitro experiments indicated that γ- or β-globulin fraction of plasma and a heat unstable and non-dialyzable substance in microsome fraction of liver cells were essential for the formation of angiotensinase G. 5. The appearance of angiotensinase G seemed to be one of the factors of an increase of plasma angiotensinase activity in liver diseases. The possible role of an increase of plasma angiotensinase activity on the contribution to the blood pressure reduction in liver diseases was discussed.
