| Research Abstract |
Biochemical properties of renin, extracted from human and rat brains, arterial walls and adrenal glands and purified by DEAE cellulose, Sephadex G-100 and concanavalin A cepharose affinity chromatography and then electrophoresis, were studied. The molecular weight, optimum pH, enzymatic kinetics, isoelectric points and glycoprotein nature of the purified renin were clarified. The contents of the brain renin of WKY rats were the highest in hypothalmus, followed by thalamus, striatum, midbrain and cerebral cortex, which were higher than those in every regions in SHR rats. Human brain renin showed a high levels of 156.3 <-!+> 33.8 ng/mg protein/h in the pineal body and 91.8 <-!+> 14.6 ng/mg protein/h in the pituitary, followed by hypothalamus and midbrain. The highest concentration of active renin was located in the renal artery, followed by the mesenteric, carotid and major aortic trunk of WKY rats. In SHR rats the renin was located in the same order, but the inactive renin in the mesent
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eric and the carotid arteries were remarkably lower in SHR than in WKY rats despite the elevated levels of the active renin in the corresponding arteries. Spectific renin and ACE activity were detected in adrenal aldosteronomas and pheochromocytomas. Molecular weights of renin were 38,000!46,000 in the pituitary, 44,000 in the pineal body, 42,000!44,000 in the thoracic aortic wall, 34,000!46,000 in aldosteronomas and 48,000 in pheochromocytoma. Optimum pH for angiotensin generation was between 6.0!6.5, and isoeletric points were 4.72!5.28, which were in good agreement with those of renins from human kidney and plasma. Furthermore, the finding of concanavalin A binding supports concept that the tissue renins contain glycoprotein residues. The results provide evidence that the tissues synthesize their own renin rather than contamination or contribution of the plasma enzyme, and that the tissue renins regulate blood pressure through secretion of autidiuretic hormone(in the pituitary), vascular contraction(in the arterial walls) and secretion of aldosterone and catecholamines(in the adrenal glands). Less
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