Effect of atrial natriuretic factor on arterial baroreceptor control of heart rate and blood pressure in conscious rats.

The effects of atrial natriuretic factor (ANF) on arterial baroreceptor control of heart rate and of blood pressure were examined in conscious normotensive rats chronically instrumented with arterial and venous catheters, by measuring (1) the pulse interval responses to four intravenous boluses of phenylephrine and four intravenous boluses of nitroprusside, reflex sensitivity being calculated as the slope of the linear relationship between pulse interval and mean arterial pressure (nine rats); (2) the pressor response to right common carotid occlusion (balloon-in-cuff occluder) in eight rats with aortic and left carotid baroreceptor denervation. The study was performed before and during a non-hypotensive infusion of ANF. Atrial natriuretic factor increased the bradycardic responses to phenylephrine by 90% but reduced the tachycardic response to nitroprusside by 67% (P less than 0.01 for both) and left the pressor response to carotid occlusion unaffected (-7%, NS). It is concluded that ANF modulates the arterial baroreceptor reflex in a complex fashion, with opposite responses to arterial baroreceptor stimulation and deactivation, and different responses for the cardiac and vascular component of the reflex.