The vasodilator potency of atrial natriuretic peptide in man.
The vasodilating potency of alpha-human atrial natriuretic peptide (alpha-hANP) was investigated in the forearms of 16 normotensive subjects, 22 to 48 (mean 28) years old, with the use of venous occlusion plethysmography. alpha-hANP, 0.005 to 1.5 micrograms/min/100 ml forearm volume (FAV), infused in nine dose steps into the brachial artery increased forearm blood flow (FAF; ml/min/100 ml FAV) from 2.8 +/- 0.4 (SEM) to a maximum of 9.6 +/- 1.1. Forearm vascular resistance (mean arterial pressure/FAF) decreased by 72%. The alpha-hANP dose that produced a 50% vasodilator response was 0.093 +/- 0.016 microgram/min/100 ml FAV (n = 11) and it resulted in a venous plasma concentration of ANP (pANP) of 115 +/- 7 pmol/liter (normal 2 to 80; radioreceptor assay). Intraindividually, the maximum dose of alpha-hANP induced an increase in FAF that was 60% of the maximum response to sodium nitroprusside (14.1 +/- 1.8). Combined infusions (n = 9) of maximum forearm vasodilator doses of alpha-hANP and nitroprusside increased FAF to 22.7 +/- 3.4; this additive vasodilator effect of alpha-hANP and nitroprusside is consistent with their different actions on the guanylate cyclase system. In man, the direct vasorelaxant effect of alpha-hANP occurs at concentrations within the upper normal range of pANP, suggesting a physiologic vasodilator role for alpha-hANP.
D000328:Adult; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005542:Forearm / Q000098:blood supply; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007261:Infusions, Intra-Arterial; D008297:Male; D008875:Middle Aged; D009599:Nitroprusside / Q000494:pharmacology; D010991:Plethysmography; D014664:Vasodilation / Q000187:drug effects*
D009599:Nitroprusside; D009320:Atrial Natriuretic Factor