Effect of angiotensin on the renal transport of sodium in essential hypertension

The renal function, including sodium excretion rates, were studied in 27 patients with early essential hypertension, before and during angiotensin infusions. The patients had a preparatory period of salt loading for four days taking a supplement of 7 g of NaCl. Determinations were made during two 30-minute periods before the angiotensin and for two 30-minute periods afterward. Arterial blood pressure was increased in all 27 patients and renal plasma flow decreased in 25. The glomerular filtration rate changes were not statistically significant, showing some increase in 15 and a decrease in 11 patients. When the group was divided into those in which there was a decrease in sodium excretion (11 patients), and those in which there was an increase in sodium excretion (16 patients), with angiotensin infusion, a correlation with the control blood pressure was evident. The patients in whom an increase occurred had a control mean blood pressure greater than 136 mm Hg, and those exhibiting a decrease of sodium excretion, a blood pressure less than 136 mm Hg. Salt excretion did not correlate with the increment in blood pressure or renal resistance changes. The minor changes in glomerular filtration of sodium of the two groups could not explain the different excretory patterns which are attributed to an alteration of the tubular transport of sodium.