Abnormal Renal Sodium Handling in Essential Hypertension. Relation to Failure of Renal and Adrenal Modulation of Responses to Angiotensin II

Abstract A continuing medical education quiz on this article (one hour of Category 1 credit) appears on page A125 of this issue. This study assessed renal sodium handling in a group of patients with essential hypertension in whom control of the renal blood supply and aldosterone release by angiotensin II is abnormal ("non-modulating") because of recent evidence that these patients have sodium-sensitive hypertension. Sixty-one patients were studied, 25 as balance was achieved with a daily sodium intake of 10 meq and 36 after a shift from a 10 meq to 200 meq sodium intake for five days. Renal and adrenal responsiveness to angiotensin II was assessed by measurement of para-aminohippurate clearance and plasma aldosterone prior to and during the infusion of 3 ng/kg per minute of angiotensin II, to identify the non-modulator group (n = 32). The half-time of the exponential function relating sodium excretion to time during the three to five days when external balance was being achieved with a 10 meq sodium intake was 23.9 ± 0.3 hours in 60 normal subjects, 24.5 ± 1.8 hours in the patients with essential hypertension in whom renal responsiveness to angiotensin II was normal, and prolonged (p