Hemodynamic Interactions of Atrial Natriuretic Factor with the Sympathetic Nervous System in Sheep

Abstract

The hemodynamic effects of short-term infusion of atrial natriuretic factor (ANF) were observed in sheep with combined α/β adrenoceptor pharmacological blockade. The effect of ANF on the sympathetically-mediated baroreflex system was observed in conscious sheep in which aortic and vena caval balloon occluders had been surgically implanted. ANF infused at 100 μ/h for 60 min produced similar effects on blood pressure, cardiac output and stroke volume during α/β–adrenoceptor blockade, compared to the responses seen in normal sheep, however the increases in heart rate and total peripheral resistance were reduced. ANF markedly enhanced the gain of the baroreceptor-heart rate reflex in the sheep. This effect may mediate the large increase in heart rate which is associated with a small fall in blood pressure during short-term infusion of ANF. In conclusion, the sympathetic

Key Words:

• ANF
• hemodynamics
• sheep
• sympathetic baroreflexes