The goal of this project was to determine the effects of elevated cardiac temperature on preload-dependent and preload-independent regulation of left ventricular developed pressure (LVDP) in Langendorff-perfused, electrically paced (420bpm), Sprague-Dawley rat hearts. LVDP responses to steady-state isoproterenol infusions (10-8M) were determined at 37, 38, 39, and 40°C. Preload-dependent LVDP was determined at 37 and 40°C. Isoproterenol-induced LVDP and preload-dependent LVDP time controls were conducted in a separate group maintained at 37°C. The percent increase in LVDP during isoproterenol infusion significantly decreased at 40°C to 42±6 (SE), compared to 55±9, 55±6, and 53±7% at 37, 38, and 39°C, respectively. No significant differences were observed in the percent increase in LVDP to isoproterenol among the corresponding time controls (50±6, 47±3, 56±4, and 56±5%). Preload-dependent LVDP decreased across the experimental protocol, but there were no cardiac temperature effects. These data indicate that β-adrenergic mediated contractility is not altered by moderate heating from normothermia but is compromised at very high temperatures (40°C). Cardiac temperatures from 37 to 40°C do not alter the inherent preload-dependent LVDP, indicating that the Frank-Starling relation is not directly affected within this temperature range.
|Number of pages||5|
|Journal||Journal of Thermal Biology|
|State||Published - Oct 2013|
Bibliographical noteFunding Information:
Authors would like to thank Sarah Hirsh for her technical assistance, Gretchen Addington for her aid with figure preparation, and the Office of Laboratory Animal Resources for housing and transportation assistance. This project was funded by the National Institute for Occupational Safety and Health Pilot Research Project Training Program of the University of Cincinnati Education and Research Center Grant #T42/OH008432-05 .
- Frank-Starling relationship
- Heat stress
- Isolated heart
- Langendorff preparation
ASJC Scopus subject areas
- Agricultural and Biological Sciences (all)
- Developmental Biology