Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2843128 | Journal of Thermal Biology | 2013 | 5 Pages |
Abstract
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 (420 bpm), Sprague-Dawley rat hearts. LVDP responses to steady-state isoproterenol infusions (10â8 M) 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.
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Authors
Richard E. Klabunde, Andrew D. LePorte, Thad E. Wilson,