Pathogenesis and reversibility of the aortic changes in experimental hypertension

In renal hypertensive female rats (Goldblatt one-kidney, one-clip model) (G 1K-1C), an increase in DNA and collagen synthesis, in the proliferation fraction of smooth muscle cells, and in wet weight were observed in the aorta as early as 4 days after the renal artery was clipped at a time when blood pressure increased rapidly. When blood pressure stabilized at high values, the metabolism of nucleic acid within the aortic media resumed its normal level. When the blood pressure level was corrected either by removal of the clip or by antihypertensive drugs, a modification of the course of the aortic proliferation changes could only be obtained when the treatment was started, at the earliest phase of hypertension. Once the proliferation changes were established, they could not be corrected even after normalization of blood pressure, at least in such short-term experiments. Moreover, some dissociation between the effect of antihypertensive drugs on blood pressure level and on arterial hypertensive disease were observed. These data illustrate the complexity of the mechanisms involved in the response of the vascular wall to high blood pressure and in its correction as well.