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Sympathetic responses to cardiopulmonary vagal afferent stimulation during development. Am J Physiol 1999 10;277(4):H1311-6

Date

10/12/1999

Pubmed ID

10516165

DOI

10.1152/ajpheart.1999.277.4.H1311

Scopus ID

2-s2.0-0032753525   13 Citations

Abstract

Previous work in our laboratory has demonstrated impairment of cardiopulmonary reflex control of renal sympathetic nerve activity (RSNA) during the newborn period. The present study was designed to test the hypothesis that this delayed maturation is secondary to incomplete central integration of vagal afferent input. Term fetal (135-140 days; n = 6), newborn (3-7 days of age; n = 8), and young adult (6-8 wk old; n = 8) sheep anesthetized with alpha-chloralose underwent vagal afferent nerve stimulation. All animals had undergone prior sinoaortic denervation to eliminate influences from the arterial baroreceptors. After determination of optimal stimulation parameters, RSNA responses to gradual increases in stimulation frequency (1.0-16 Hz) were recorded and compared by one-way ANOVA. RSNA decreased progressively with increased frequency of stimulation in all three groups of animals. When comparing the three groups at any given frequency of stimulation, reflex withdrawal of RSNA tended to be more pronounced in newborn lambs (P < 0.05 for 1 and 4 Hz). Heart rate (HR) was also noted to decrease significantly with vagal afferent stimulation in each of the groups, but no significant differences in the reflex decreases in HR were noted among the three groups of animals. These results demonstrate that central integration of vagal afferent input is intact in fetal and newborn sheep. These results suggest that the delayed maturation of cardiopulmonary reflex-mediated changes in RSNA seen early in development appears to depend on intrinsic alterations in baroreceptor function rather than incomplete central integration.

Author List

Merrill DC, Segar JL, McWeeny OJ, Robillard JE

Author

Jeffrey L. Segar MD Professor in the Pediatrics department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Afferent Pathways
Aging
Animals
Animals, Newborn
Electric Stimulation
Fetus
Heart
Lung
Sheep
Sympathetic Nervous System
Vagus Nerve
jenkins-FCD Prod-478 d1509cf07a111124a2d122fd3df854cc0b993c00