Central vagal activation by alpha2-adrenergic stimulation is impaired in spontaneously hypertensive rats

T. Kawada, T. Akiyama, S. Shimizu, A. Kamiya, K. Uemura, Y. Sata, M. Shirai, M. Sugimachi

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Aim: To elucidate the abnormality of vagal control in spontaneously hypertensive rats (SHR) by measuring left ventricular myocardial interstitial acetylcholine (ACh) release in response to α2-adrenergic stimulation as an index of in vivo vagal nerve activity. Methods: A cardiac microdialysis technique was applied to the rat left ventricle in vivo, and the effect of α2-adrenergic stimulation by medetomidine or electrical vagal nerve stimulation on myocardial interstitial ACh levels was examined in normotensive Wistar-Kyoto rats (WKY) and SHR under anaesthetized conditions. Results: Intravenous medetomidine (0.1 mg kg-1) significantly increased the ACh levels in WKY (from 2.4 ± 0.6 to 4.2 ± 1.3 nmol L-1, P < 0.05, n = 7) but not in SHR (from 2.5 ± 0.7 to 2.7 ± 0.7 nmol L-1, n = 7). In contrast, electrical vagal nerve stimulation increased the ACh levels in both WKY (from 1.0 ± 0.4 to 2.9 ± 0.9 nmol L-1, P < 0.001, n = 6) and SHR (from 0.9 ± 0.2 to 2.2 ± 0.4 nmol L-1, P < 0.001, n = 6). Intravenous administration of medetomidine (0.1 mg kg-1) did not affect the vagal nerve stimulation-induced ACh release in either WKY or SHR. Conclusion: Medetomidine-induced central vagal activation was impaired in SHR, whereas peripheral vagal control of ACh release was preserved. In addition to abnormal sympathetic control, vagal control by the central nervous system may be impaired in SHR.

Original languageEnglish
Pages (from-to)72-79
Number of pages8
JournalActa Physiologica
Volume206
Issue number1
DOIs
Publication statusPublished - Sep 1 2012
Externally publishedYes

Keywords

  • Acetylcholine
  • Cardiac microdialysis
  • Medetomidine
  • Rats
  • Vagal nerve stimulation

ASJC Scopus subject areas

  • Physiology

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