Effect of age and gender on thermoregulation

R. B. McDonald, C. Day, K. Carlson, J. S. Stern and B. A. Horwitz Department of Nutrition, University of California, Davis 95616. Previous investigations have shown that during cold exposure 24-mo-old male Fischer 344 (F344) rats do not thermoregulate as well as do 12-mo-old animals. To determine if...

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Veröffentlicht in:American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 1989-10, Vol.257 (4), p.700-R704
Hauptverfasser: McDonald, R.B. (University of California, Davis, CA), Day, C, Carlson, K, Stern, J.S, Horwitz, B.A
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Sprache:eng
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Zusammenfassung:R. B. McDonald, C. Day, K. Carlson, J. S. Stern and B. A. Horwitz Department of Nutrition, University of California, Davis 95616. Previous investigations have shown that during cold exposure 24-mo-old male Fischer 344 (F344) rats do not thermoregulate as well as do 12-mo-old animals. To determine if this deficiency also occurs in female rats, we measured oxygen consumption (thermogenesis) and colonic temperature of male and female rats 5, 23, and 27 mo of age at rest and during 6 h of exposure to 6 degrees C. In addition, nonshivering thermogenesis (NST) was evaluated from the capacity of brown adipose tissue (BAT) mitochondria isolated from cold-exposed rats to bind guanosine 5'-diphosphate (GDP). Neither age nor gender had a significant effect on resting or cold-exposed oxygen consumption expressed on a mass-independent basis (l/kg body mass0.67) or on a lean body mass independent basis (l/kg lean body mass0.67). The drop in colonic temperature in response to cold was greater in the male rats. However, females exhibited increased BAT mass and relatively constant GDP binding with advancing age, whereas males showed decreased mass and GDP binding. Although the data suggest greater NST capacity in the female rats, rates of cold-induced oxygen consumption were similar in older female vs. male rats. Taken together, our data indicate that gender has a significant impact on thermoregulation and that, under the cold exposure conditions of the study, this effect involves differential heat conservation rather than heat production.
ISSN:0002-9513
0363-6119
2163-5773
1522-1490
DOI:10.1152/ajpregu.1989.257.4.R700