[Angiotensin-converting enzyme activity of the aorta in experimental hypertensive rats]

Angiotensin-converting enzyme activity of the aortic subcellular fractions (homogenate, mitochondria, microsomes and supernatant) was determined in normotensive and experimental hypertensive rats (1-clip, 1-kidney Goldblatt hypertensive; 1-clip, 2-kidney Goldblatt hypertensive and 2-clip, 2-kidney hypertensive rats). The systolic blood pressure markedly elevated in each group of experimental hypertensive rats, while it did not in normotensive rats. Angiotensin-converting enzyme activity was consistently high in the microsomal and supernatant fractions of the aorta in experimental hypertensive rats as well as in normotensive rats. However, the enzyme activity from each fraction of the aorta in 1-clip, 2-kidney Goldblatt hypertensive rats was significantly higher than that in normotensive and other experimental hypertensive rats. There was no significant difference in the enzyme activity among normotensive, 1-clip, 1-kidney Goldblatt hypertensive and 2-clip, 2-kidney hypertensive rats. The angiotensin-converting enzyme, widely distributed in subcellular fractions of the aorta, may play a possible role in the local control of vascular tone. It seems likely that increased angiotensin-converting enzyme activity in arterial tissue contributes to the initiation or development of hypertension in 1-clip, 2-kidney Goldblatt hypertension in rats.