Study of renovascular hypertension in rats. IV. Renal arterial blood velocity in one-clip, two-kidney hypertensive rats.

In one-clip, two-kidney hypertensive models of rats, the renal arterial blood velocity was recorded using the bidirectional Doppler velocimeter before and at various times after clipping of the renal arteries. In all the rats, immediately after placement of a clip, the blood velocity of the stenosed artery was lowered significantly. Although the blood velocity remained low 2 weeks after clipping, it recovered to the pre-clip level at 6 and at 11 to 13 weeks after clipping. The plasma renin activity tended to decrease following the acute, high-renin stage of hypertension. If it can be assumed that the blood velocity is one of the indexes representing blood flow, its return to the pre-clip normal level in the chronic stage of renovascular hypertension may signify recovery of blood flow to the clipped kidney leading to a reduction in renal renin synthesis and consequently a decrease in plasma renin activity.