TY - JOUR
T1 - Vagal C-fiber blockade abolishes sympathetic inhibition by atrial natriuretic factor
AU - Schultz, H. D.
AU - Gardner, D. G.
AU - Deschepper, C. F.
AU - Coleridge, H. M.
AU - Coleridge, J. C.G.
PY - 1988
Y1 - 1988
N2 - 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.
AB - 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.
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M3 - Article
C2 - 2969196
AN - SCOPUS:0023733999
VL - 255
SP - 24/1
JO - American Journal of Physiology - Renal Physiology
JF - American Journal of Physiology - Renal Physiology
SN - 0363-6127
IS - 1
ER -