Biochemical Studies on Blood Pressure Regulation
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概要
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The present studies consist of purification of angiotensinase in red blood cells from rabbits and isolation of a depressor principle in microsome fraction of liver cells from rabbits.<BR>The purification of angiotensinase was carried out by fractionation with ammonium sulfate between 20-70 % saturation, DEAE cellulose column chromatography and Sephadex G-200 gel filtration, by using rabbit hemolysate. Specific activity of angiotensinase on the purified preparation was about 8,000 fold increased in comparison with that of crude hemolysate. The enzyme preparation showed a hydrolytic activity on L-leucyl-β-naphthylamide, which, however, had no hydrolytic activities on leucinamide, L-aspartyl-β-naphthylamide, Leu-Gly, D, L-Glu-Gly, Arg-Ala, Cbz-Gly-Phe, Cbz-Gly-Arg, casein, TAME and ATEE. The incubation mixture of the enzyme and synthetic α-L-Asp<SUP>1</SUP>-Ileu<SUP>5</SUP>-angiotensin II demonstrated nynhidrin positive 5 spots by paper electrophoresis, indicating Ileu-His-Pro-Phe, angiotensin II, Asp-Arg, Val-Tyr and isoleucine. These findings suggested the purified enzyme from red blood cells might be chymotrypsin like endopeptidase and relatively specific to angiotensin. Subcutaneous injection of the enzyme inhibited development of hypertension in the acute stage of experimental renal hypertensive rats.<BR>The depressor principle, located only in microsome fraction of normal rabbit liver cells by the method of Schneider, was isolated by heat treatment, fractionation of ammonium sulfate between 0-70 % saturation of the supernatant, DEAE Sephadex A-50 column chromatography and zone electrophoresis. Intravenous injection of the principle showed relatively a long sustained depressor effect in comparison with that of bradykinin or adenosine in a normal rabbit and rat. The ultraviolet absorption maximum of the principle was 256 mμ. The mean molecular weight was 36,000 by Archibald method and about 90% was RNA. Nucleotide analysis showed CMP 20%, UMP 14%, AMP 7% and GMP 59%.<BR>Significance of angiotensinase from plasma and red blood cells and the depressor principle, RNA, from liver on the humoral regulation of blood pressure levels were discussed.
- Japan Society of Clinical Chemistryの論文