α2-adrenergic modulation of colonic tone during hyperventilation

Adil E. Bharucha, Vera Novak, Michael Camilleri, Alan R. Zinsmeister, Russell B. Hanson, Phillip A. Low

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

Our aims were to assess the role of adrenergic modulation in the hyperventilation-induced increase in colonic tone. Of 40 healthy volunteers, 12 received placebo (saline) and the remaining 28 received either clonidine, yohimbine, phenylephrine, or ritodrine. Time-frequency mapping of heart rate based on Wigner distribution assessed variations in parasympathetic and sympathetic activity during hyperventilation. Tone in the descending colon was recorded by a barostat balloon before, during, and after 5 min of hyperventilation. Heart rate spectral analysis suggested diminished sympathetic and vagal activity during hyperventilation and increased sympathetic and vagal activity after hyperventilation. Adrenergic agents influenced (P = 0.01) the tonic response after, but not during, hyperventilation. Yohimbine reduced the increment in colonic tone after hyperventilation compared with saline (P < 0.05) and clonidine (P = 0.002); phenylephrine and ritodrine had no effects. Different mechanisms modulate the increase in colonic tone during and after hyperventilation. Yohimbine attenuates the increase in colonic tone after hyperventilation probably by enhancing inhibitory sympathetic input to the colon.

Original languageEnglish (US)
Pages (from-to)G1135-G1140
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume273
Issue number5 36-5
DOIs
StatePublished - 1997

Keywords

  • Spectral analysis of heart rate

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

Fingerprint Dive into the research topics of 'α<sub>2</sub>-adrenergic modulation of colonic tone during hyperventilation'. Together they form a unique fingerprint.

  • Cite this