脳内ならびに大動脈内アンジオテンシンI・変換酵素活性に対する食塩負荷の影響

―高血圧自然発症ラットならびに脳卒中易発症ラットにおける検討―

抄録

The efiect of sodium intake on angiotensin-converting enzyme activity was studied in five areas of the brain (the cerebral cortex, midbrain, striatum, thalamus and hypothalamus) and in subcellular fractions of the aorta (homogenate, mitochondria, microsomes and supernatant) in normotensive, spontaneously hypertensive and stroke-prone spontaneously hypertensive rats. Angiotensin-converting enzyme activity was signiffcantly higher in the hypothalamus than in the other areas of the brain in spontaneously hypertensive rat. The enzyme activity of subcellular fractions of the aorta showed an extremely high value in the supernatant in normotensive, spontaneously hypertensive and stroke-prone spontaneously hypertensive rats. Sodium intake resulted in a marked decrease in the aortic converting enzyme activity from each fraction in each rat, while it did in a significant rise of the enzyme activity in the midbrain of spontaneously hypertensive rat, and also in the midbrain and the striatum of stroke-prone spontaneously hypertensive rat. It is likely therefore that sodium intake lowers the converting enzyme activity or content of the aorta. Increased activity of the converting enzyme of the brain of spontaneously hypertensive and stroke-prone spontaneously hypertensive rats may play a possible role in hypertension induced by a high circulating sodium level through much more convertion of angiotensin I into angiotensin II in the brain.