Time course of the enhanced blood pressure response to reinduction of renal artery stenosis in unclipped renal hypertensive rats.

Moderate or severe hypertension was induced in rats by application of a clip 0.25 or 0.20 mm internal diameter) to the left renal artery leaving the contralateral kidney intact. Removal of the clip 6, 13 or 24 days after the induction of the hypertension was followed by a rapid decrease in blood pressure. A near normotensive level was reached after 2--6 h. Reapplication of the clip to the unclipped renal artery after 1 day caused an enhanced blood pressure response. The preoperative hypertensive levels were reached within 2 h. This enhanced response was related to the level of blood pressure before the removal of the clip. Lengthening the interval between removal and reapplication of the clip gradually reduced the enhanced response of blood pressure, which had disappeared 8 days after the removal of the clip. Reapplication of the clip to the contralateral renal artery was not followed by an enhanced response in rats with previous moderate or severe hypertension.