Nitroprusside, but not ANF inhibits venoconstriction in an in situ rat model

Potential venodilator actions of nitroprusside (10 and 50 μg/min) and ANF (23 amino acid rat sequence, 10 and 30 μg/min) were assessed in rats subjected to cardiopulmonary bypass. Norepinephrine (NE, 10 μg) caused arterial pressor, i.e. increased perfusion pressure and venoconstrictor, i.e. increased venous flow, effects. ANF infusion failed to alter NE-induced pressor and venoconstrictor effects while nitroprusside significantly inhibited NE responses. Thus nitroprusside but not ANF, shows venodilator properties in this in situ rat model.