Vasodilator properties of atrial natriuretic factor: a comparison with nitroglycerin, nitroprusside, and phentolamine during cardiopulmonary bypass.

Thirty-five patients scheduled for coronary artery surgery were studied during hypothermic cardiopulmonary bypass (CPB) to compare the arteriolar and venodilator properties of a bolus dose of atrial natriuretic factor (ANF), 100 micrograms, with those of nitroglycerin, 200 micrograms, sodium nitroprusside, 120 micrograms, phentolamine, 3 mg, and placebo. A decrease observed in mean arterial pressure was used as an indicator of a decrease in systemic vascular resistance (arteriolar dilation), while a decrease in reservoir blood volume of the CPB circuit was considered to indicate an increase in venous capacitance (venodilation). All vasodilators decreased mean arterial pressure, and there was no difference in the maximal decrease of the pressure between the drugs. However, the decrease caused by ANF appeared later than that caused by the other vasodilators and lasted longer than with nitroglycerin and sodium nitroprusside. Nitroglycerin and sodium nitroprusside decreased reservoir blood volume, while ANF and phentolamine had no effect. It is concluded that ANF is an arteriolar dilator with a time profile of its effect differing from those of nitroglycerin, sodium nitroprusside, and phentolamine. ANF seems to have no venodilator activity in patients undergoing hypothermic CPB.