Effects of β-adrenergic agonists on splanchnic vascular volume and cardiac output

P. I. Chang, D. L. Rutlen

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

The effect of β-adrenergic agonists on splanchnic intravascular volume (SIV), measured with radionuclide imaging, and the subsequent influence of such volume changes on cardiac output (CO) were examined in 40 anesthetized dogs. Isoproterenol (6 μg/min) caused a decrease in total SIV of 12 ± 1% (P < 0.001). The decrease was due entirely to a decrease in splenic volume of 24 ± 3% (P < 0.001), since volume increased in the remainder of the splanchnic vasculature [hepatic and mesenteric volume increased 12 ± 2% (P < 0.001) and 11 ± 3% (P < 0.02), respectively]. CO increased from 1,724 ± 187 to 3,138 ± 321 ml/min (P < 0.001); after subsequent splenectomy, isoproterenol caused a similar increment. Isoproterenol-associated SIV changes were not altered by carotid denervation and vagotomy or by β1-adrenergic inhibition with metoprolol but were abolished by nonselective β-adrenergic inhibition with propranolol. With a larger dose of metoprolol and smaller dose of isoproterenol to minimize β1-adrenergic effects, the isoproterenol-associated CO increment was attenuated (P < 0.01) by splenectomy. With the β2-agonist terbutaline (41 μg/min) after metoprolol, total SIV decreased 15 ± 4% (P < 0.001). After subsequent α-adrenergic inhibition with phenoxybenzamine, terbutaline caused no change in SIV and an attenuated (P < 0.05) increase in CO. Thus β-adrenergic agonist administration causes a decrease in total SIV due entirely to a decrease in splenic volume. The SIV decrement is dependent on β2- and α-adrenoceptor stimulation and appears to enhance CO only if β1-adrenergic effects are minimized.

Original languageEnglish (US)
Pages (from-to)H1499-H1507
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume261
Issue number5 30-5
StatePublished - 1991
Externally publishedYes

Keywords

  • Capacity vessels
  • Isoproterenol
  • Liver
  • Mesentery
  • Spleen
  • Terbutaline
  • Veins

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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