Beta-blockers and renal function.

alpha-, beta 1- and beta 2-adrenergic receptors in the kidney mediate vasoconstriction, renin secretion and vasodilatation, respectively. Blockade of beta-receptors may therefore be expected to influence renal blood flow and possibly glomerular filtration rate by intrarenal effects as well as by reducing cardiac output and blood pressure. Since the various beta-adrenergic blocking drugs available differ in the degree to which they block beta 2-receptors (cardioselectivity) and also in their intrinsic sympathomimetic activity, they would be expected to have different effects on renal function. The acute administration of beta-blockers usually results in a reduction in effective renal plasma flow and glomerular filtration rate, whether or not the drug is cardioselective or has intrinsic sympathomimetic activity, with the exceptions of nadolol, which has actually increased effective renal plasma flow in some studies and of tolamolol. With chronic oral administration, the non-cardioselective beta-blockers reduced glomerular filtration rate and effective renal plasma flow. The cardioselective drugs do not usually produce significant reductions in glomerular filtration rate or effective renal plasma flow, although small increases in serum urea during treatment do occur. Interestingly, in contrast to findings with intravenous administration, orally administered nadolol produced a slight reduction in glomerular filtration rate in 1 study, so the effect of this agent on renal function under clinical conditions remains uncertain. It seems likely that beta-blockers reduce renal function predominantly by blocking beta 2-receptors in the kidney. To keep area of discussion in perspective, it is important to realise that although there have been isolated reports of serious deterioration in renal function coinciding with beta-blocker treatment, the great majority of reports are of reduction in glomerular filtration rate which are not of clinical significance, even in patients with pre-existing impairment of renal function. The beta-blockers with low lipid solubility-i.e. atenolol, nadolol and sotalol-are not metabolised, and their dose must be reduced in renal failure. Propranolol has active metabolites and its dose must also be reduced slightly in uraemia.