Impairment of thermogenesis and heat conservation in rats during 3 hours of 3-G exposure
Monson, C.B.; Horowitz, J.M.
Aviation Space and Environmental Medicine 55(6): 542-545
1984
ISSN/ISBN: 0095-6562 PMID: 6466250 Document Number: 225877
Heat conservation and production were studied in rats at 3 G and at 1 G. A closed-circuit system that includes a Krogh-type spirometer for the continuous measurement of oxygen consumption was used to determine heat production. At the same time, core temperature (Tc) and tail temperature (Tt) were also measured. During the first 20 min at 3 G, oxygen consumption increased by at most 18% in some of the rats and fell by up to 15% in the remaining rats. However, in all rats at 3 G, there was a fall of Tc during this time. Thus, the initial fall of Tc at 3 G was independent of concurrent changes in the rate of oxygen consumption. Furthermore, the rapid fall in Tc during the initial exposure to hypergravity was not due to reduced heat production (since oxygen consumption was variable and in some rats increased) but to an increase in heat loss. Even after 3 h at 3 G, when heat conservation mechanisms had recovered, the rate of oxygen consumption in rats was not significantly increased relative to the 1 G rate; hence thermogenesis was not activated to rewarm the animal.