Exchangeable sodium, plasma renin activity and blood pressure changes during the development of 2 kidney 1 clip hypertension, and after subsequent contralateral nephrectomy.

Sequential changes in exchangeable sodium, fluid intake, blood pressure and plasma renin activity were measured in 2K1C hypertensive rats during the development of severe hypertension. Exchangeable sodium was measured by the equilibration of the rats' exchangeable sodium with radioactive saline. In rats drinking saline, both PRA and exchangeable sodium levels increased as hypertension developed, and captopril induced large falls in blood pressure. Subsequent removal of the contralateral kidney reduced PRA, but did not alter exchangeable sodium or blood pressure. Captoril had no effect on blood pressure. It is concluded that the rise in PRA in 2K1C hypertension depends on the presence of the contralateral kidney, but occurs in the absence of sodium depletion.