Thermogenic responses of brown adipocytes to noradrenaline and glucagon in heat-acclimated and cold-acclimated rats.

Heat production of isolated brown-fat cells by addition of noradrenaline and glucagon was measured in warm-acclimated control, cold-acclimated and heat-acclimated rats by use of a twin-type conduction microcalorimeter. Noradrenaline and glucagon induced maximum heat production per 10(6) cells in dose of 1 microgram/ml. Heat produced by maximum thermogenic response to glucagon was twice as much as that to noradrenaline. Thermogenic response to noradrenaline was markedly increased in cold-acclimated brown adipocytes, while it was reduced in heat-acclimated ones. Thermogenic response to glucagon was significantly reduced in heat-acclimated brown adipocytes, while it was not affected in cold-acclimated brown adipocytes.