In vivo atrial peptide-venodilation: minimal potency relative to nitroglycerin in dogs.
Venodilation is thought to contribute to the hemodynamic actions of atrial peptides. Therefore, we measured the effective vascular compliance (EVC) as a parameter of overall venous tone in 7 pentobarbital anesthetized dogs under autonomic blockade during i.v. infusions of rat atriopeptin II (AP II, up to 100 pmol/kg/min), rat alpha-atrial natriuretic factor, and nitroglycerin (GTN). AP II lowered mean arterial pressure by reducing peripheral vascular resistance with a threshold between 3 and 10 pmol/kg/min (but was ineffective in anesthetized or conscious dogs without autonomic blockade). Neither atrial peptide altered EVC, while GTN augmented EVC and caused a 4.6-fold larger reduction of central venous pressure than AP II at equihypotensive dosage. These findings, with infusion rates probably close to endogeneous release, reveal a vasodilator potency of atrial peptides, which is restricted to systemic arterioles without affecting venous tone.
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D001340:Autonomic Nerve Block; D001794:Blood Pressure / Q000187:drug effects; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D005996:Nitroglycerin / Q000494:pharmacology*; D014655:Vascular Resistance / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*; D014680:Veins / Q000187:drug effects
D009320:Atrial Natriuretic Factor; D005996:Nitroglycerin