Changes in cardiovascular β-adrenoceptor responses during hypothermia

Young Soo Han, Torkjel Tveita, Timofei V. Kondratiev, Y. S. Prakash, Gary C. Sieck

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

The purpose of this study was to determine cardiovascular β-adrenergic responses during hypothermia. In the present study, we used isoproterenol (Iso), a nonselective, potent β-adrenoceptor agonist, well known for its positive chronotropic and inotropic pharmacologic actions at normothermia. Rats were instrumented to measure mean arterial pressure (MAP) and left ventricular (LV) pressure-volume changes using a Millar pressure-volume conductance catheter. Core temperature was manipulated from 37 (normothermia) to 24 °C (hypothermia) and back to 37 °C (rewarming) using both internal and external heat exchangers. During cooling at each temperature (33, 30, 27, and 24 °C), central hemodynamic variables and MAP were measured while intravenously infusing Iso (doses of 1.7, 5, 10, and 20 ng/min). Seven animals underwent all phases of the protocol. At normothermia Iso infusion resulted in a significant, dose-dependent increase in heart rate (HR), stroke volume (SV), cardiac output (CO), LV dP/dtmax (left ventricular maximum derivative of systolic pressure over time) but no change in MAP. During cooling Iso infusion caused no dose-dependent change in any of the hemodynamic variables. After rewarming, baseline HR and LV dP/dtmax were increased, whereas SV was significantly reduced when compared with their pre-hypothermic baseline values. This study shows that physiological cardiovascular responses mediated by the β-adrenoceptor are significantly diminished during core hypothermia.

Original languageEnglish (US)
Pages (from-to)246-250
Number of pages5
JournalCryobiology
Volume57
Issue number3
DOIs
StatePublished - Dec 1 2008

Keywords

  • Cardiovascular function
  • Cold
  • Hypothermia
  • Isoproterenol
  • Rat
  • Temperature

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

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