Administration of atrial natriuretic factor (ANF) to anesthetized rats decreases renal nerve activity (RNA), an effect prevented by vagotomy but not by atropine. We sought to determine whether afferent vagal C-fibers mediate the inhibition of sympathetic outflow. ANF (2.5 μg/kg iv) decreased mean arterial pressure (MAP) by 25 ± 2 mmHg, RNA by 11 ± 5%, and least splanchnic nerve activity (LSNA) by 10 ± 4% in anesthetized rats with arterial baroreceptors intact, and by 40 ± 3 mmHg, 28 ± 7%, and 23 ± 4%, respectively, in sinoaortic-denervated rats. Inhibition of RNA and LSNA by ANF was reduced slightly by cooling the vagi to 6 or 7°C, a temperature at which conduction in A-fibers was blocked and that in C-fibers attenuated; inhibition was abolished when C-fibers were blocked by cooling to 0°C. We conclude that the inhibition of RNA and LSNA by ANF was mediated by afferent vagal C-fibers. We also obtained evidence that the aortic nerves contribute to ANF-induced inhibition of RNA. Our results support the notion that ANF evokes a generalized decrease in sympathetic tone that contributes to the hypotension, cardiac inhibition, and natriuresis accompanying systemic administration of the peptide.
|Original language||English (US)|
|Journal||American Journal of Physiology - Regulatory Integrative and Comparative Physiology|
|State||Published - Jan 1 1988|
ASJC Scopus subject areas
- Physiology (medical)