Significance of adrenoceptor-mediated atrial natriuretic factor release in normal humans

To assess the potential role of adrenoceptor-stimulated atrial natriuretic factor (ANF) release in healthy humans, 18 volunteers, divided into groups of six, underwent experiments with infusion of incremental doses of salbutamol with and without beta-blockade with propranolol, propranolol alone, and bolus injections of clonidine before and after alpha-blockade with phentolamine, and phentolamine alone. Since changes in right atrial pressure have been shown to influence ANF release, central venous pressure (CVP) was continuously measured 30 min before, during the 120 min duration of drug infusions, and for 30 min after the bolus injections of the drugs. ANF was serially determined in central venous plasma during all drug infusions, and plasma catecholamines were measured to determine any possible influence of endogenous sympathetic activation on ANF levels. Plasma ANF was unaffected by all individual drugs and drug combinations, despite significant reductions in CVP in the salbutamol, phentolamine and phentolamine + clonidine groups, and a doubling of heart rate during salbutamol administration (p less than 0.01 for all). The results do not suggest a major role for adrenoceptor-mediated ANF release in normal humans, and do not indicate that plasma ANF levels are determined by tonic inhibition or facilitation of the sympathetic nervous system.