Abstract
The FOK rat was established as an inbred strain with genotypic adaptation to a hot environment. To investigate the mechanism of the heat resistance of FOK rats, heat production by isolated brown adipocytes in FOK and WKAH rats was measured at 37.0 and 39.9C. Basal heat production by brown adipocytes of FOK rats was not significantly different from that of WKAH rats. Isoproterenol increased the heat production in a dose-dependent manner in both strains, while 10-9 M isoproterenol caused a significant increase in WKAH rats and a negligible change in FOK rats. These results indicate that the reason why FOK rats are resistant to the severe heat is partly due to the low heat production by brown adipocytes.
