Separate renal function studies in conscious dogs with renovascular hypertension

A new method was developed for separate kidney function studies by catheterizing the ureters and exteriorizing the catheters through the urethra into the vagina. Renal artery plication was performed to reduce blood flow to one kidney by 66 +/- 5%. Arterial pressure increased from 107 +/- 2 to 131 +/- 3 mmHg and remained elevated for 28 days. Plasma renin activity was increased for the first 7-10 days only. Sodium and water excretion were markedly reduced in the kidney with the stenosed renal artery and after the first 2 days Na and water excretion were incresed in the contralateral kidney. These changes in Na and water excretion were frequently associated with similar directional changes in glomerular filtration rate (GFR) and renal plasma flow. An exception was noted in that renal sodium and water excretion remained low throughout the 28 days in the kidney with the constricted renal artery, whereas GRF returned to near the control level by the end of 2 wk. Altered filtration fraction did not appear to be a determining factor in control of the rate of Na excretion. It is suggested that GFR, the renin-angiotensin-aldosterone system, and other as yet undefined factors are involved in salt and water homeostasis during unilateral renal artery stenosis with hypertension.