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Heat acclimation does not alter rat mesenteric artery response to norepinephrine
R C Looft-Wilson1, R D Matthes, C V Gisolfi
1Department of Physiology and Biophysics, Bowen Science Building, The University of Iowa, Iowa City, Iowa 52242, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|February 4, 1999
Summary
Heat acclimation does not change how rat mesenteric arteries respond to norepinephrine (NE). This study found no difference in NE sensitivity between heat-acclimated and control rats, even at elevated temperatures.
Area of Science:
- Physiology
- Thermoregulation
- Vascular Biology
Background:
- Heat acclimation is known to increase the temperature threshold for heat-induced splanchnic vasoconstriction in rats.
- Understanding the vascular mechanisms underlying heat acclimation is crucial for thermoregulatory research.
Purpose of the Study:
- To investigate whether heat acclimation alters the sensitivity of rat splanchnic resistance arteries to norepinephrine (NE).
Main Methods:
- Male Sprague-Dawley rats were divided into heat-acclimated (35°C) and control (22-23°C) groups.
- Small mesenteric artery segments were isolated, cannulated, pressurized, and exposed to cumulative doses of NE (10⁻⁹ to 10⁻⁵ M).
- Artery diameter changes were measured using video microscopy at 37°C and 43°C bath temperatures.
Main Results:
- No significant differences in norepinephrine-induced constriction responses were observed between heat-acclimated and control rat arteries.
- These findings held true at both physiological (37°C) and elevated (43°C) temperatures.
Conclusions:
- Heat acclimation does not alter the sensitivity of rat mesenteric arteries to norepinephrine.
- The vascular response to NE in splanchnic resistance arteries is not a mechanism affected by heat acclimation in rats.