Differential baroreflex control of sympathetic drive by angiotensin II in the nucleus tractus solitarii

J. W. Polson, R. A L Dampney, P. Boscan, A. E. Pickering, J. F R Paton*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)

Abstract

Microinjection of angiotensin II into the nucleus tractus solitarii attenuates the baroreceptor reflex-mediated bradycardia by inhibiting both vagal and cardiac sympathetic components. However, it is not known whether the baroreflex modulation of other sympathetic outputs (i.e., noncardiac) also are inhibited by exogenous angiotensin II (ANG II) in nucleus tractus solitarii (NTS). In this study, we determined whether there was a difference in the baroreflex sensitivity of sympathetic outflows at the thoracic and lumbar levels of the sympathetic chain following exogenous delivery of ANG II into the NTS. Experiments were performed in two types of in situ arterially perfused decerebrate rat preparations. Sympathetic nerve activity was recorded from the inferior cardiac nerve, the midthoracic sympathetic chain, or the lower thoracic-lumbar sympathetic chain. Increases in perfusion pressure produced a reflex bradycardia and sympathoinhibition. Microinjection of ANG II (500 fmol) into the NTS attenuated the reflex bradycardia (57% attenuation, P < 0.01) and sympathoinhibition of both the inferior cardiac nerve (26% attenuation, P < 0.05) and midthoracic sympathetic chain (37% attenuation, P < 0.05) but not the lower thoracic-lumbar chain (P = 0.56). We conclude that ANG II in the nucleus tractus solitarii selectively inhibits baroreflex responses in specific sympathetic outflows, possibly dependent on the target organ innervated.

Original languageEnglish
Pages (from-to)R1954-R1960
Number of pages7
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume293
Issue number5
DOIs
Publication statusPublished - Nov 2007
Externally publishedYes

Keywords

  • Baroreceptor reflex
  • Blood pressure
  • Vagal

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