Study of renovascular hypertension in rats: I. The role of the contralateral, non-clipped kidney in two-kidney, one-clip hypertension in rats.

We attempted to produce two-kidney one-clip renovascular hypertension in SD rats, using hemoclips 0.2mm in diameter. After 12 weeks, 10 of the 16 rats were hypertensive. At this point, one-kidney, one-clip models were prepared by contralateral nephrectomy in five of the 10 hypertensive rats and in all six normotensive rats. Postoperatively, these 11 rats developed hypertension. Four to 6 weeks later, the clip was removed from the renal artery in five two-kidney and 11 one-kidney hypertensive rats. After unclipping, all the rats became normotensive although the extent of the fall in blood pressure in the one-kidney model was significantly greater than in the two-kidney model. The roles of the contralateral non-clipped kidney in the evolution of two-kidney, one-clip Goldblatt hypertension appear to be dual; sometimes depressing elevated blood pressure and sometimes maintaining it. Thus, it is postulated that in the six initially normotensive rats, its action was predominantly antihypertensive, while in the other 10 hypertensive rats, the presence of a contralateral non-clipped kidney served to develop and maintain hypertension even after unclipping.