Radioisotopic renal function studies in essential hypertension.

Renal and intrarenal distribution of flow together with an index of cardiac output is measurable using a single injection of 123I-o-iodohippurate. The argument is presented that in the treatment of essential hypertension one should avoid using drugs that reduce renal blood flow, a property of chronic therapy with most beta-blockers or diuretics. Reduction of renal blood flow is a stimulus to salt retention and renin release which tend to maintain hypertension. Drugs which increase renal blood flow, thereby augmenting the renal loss of salt and decreasing renin release, tend to reduce hypertension in the long term.