A direct calorimetric system for the continuous recording of heat balance of freely moving small animals.

A system has been designed which provides for simultaneous measurements of heat loss and heat production of freely moving rodents under restricted feeding schedules.The system includes specially designed calorimeter，an air suppier and flow regulators，air remperature controllers，a thermobath for heat sink temperature regulation，humidity sensing devices or a platemeter，O_2and CO_2analyzers and a data logger and a personal computer。The over-all response time and the sensitivity of the calorimeter are less than 5min and 0.499W/mV at a calorimeter remperature of 25°c.Heat production was estimated from continuous measurements of O_2consumption and CO_2production，and changes in heat balnce were computed with the personal computer.Using this system，following results were obtained。1)Effects of peptides injected into the cerebroventricle are in different directions in heat loss response with different peptide-groups.2)A clear daily difference in temperature regulatory responses to body warming exists when rats are physically restrained，but not when they were allowed to move freely.3)The effects of intermittent and continuous heat exposures are different according to the mode of heat exposure to obtain heat acclimation in rats.4)Food restricted rats(2hours Feeding Only In A Day)enhance wheel running activity several hours before and after the feeding time。The relationship between wheel running and average heat production was not different between pre-and post feeding periods and control ad-lib feeding period.5)Fasting suppresses heat loss response to intravenous injections of endotoxin and endogenous pyrogens but not to intracerebroventricular injections。Several other experiments were also conducted。

A system has been designed which provides for simultaneous measurements of heat loss and heat production of freely moving rodents under restricted feeding schedules. The system includes specially designed calorimeter, an air suppier and flow regulators, air remperature controllers, a thermobath for heat sink temperature regulation, humidity sensing devices or a platemeter, O_2 and CO_2 analyzers and a data logger and a personal computer. The over-all response time and the sensitivity of the calorimeter are less than 5 min and 0.499 W/mV at a calorimeter remperature of 25゜c. Heat production was estimated from continuous measurements of O_2 consumption and CO_2 production, and changes in heat balnce were computed with the personal computer. Using this system, following results were obtained. 1) Effects of peptides injected into the cerebroventricle are in different directions in heat loss response with different peptide-groups. 2) A clear daily difference in temperature regulatory responses to body warming exists when rats are physically restrained, but not when they were allowed to move freely. 3) The effects of intermittent and continuous heat exposures are different according to the mode of heat exposure to obtain heat acclimation in rats. 4) Food restricted rats (2 hours feeding only in a day) enhance wheel running activity several hours before and after the feeding time. The relationship between wheel running and average heat production was not different between pre- and post feeding periods and control ad-lib feeding period. 5) Fasting suppresses heat loss response to intravenous injections of endotoxin and endogenous pyrogens but not to intracerebroventricular injections. Several other experiments were also conducted.