Relationship between the Environmental Temperature and Heart Rate, Respiratory Rate and Heat Production in Mice

Abstract

The heart rate, respiratory rate and heat production in unrestrained mice in accordance with changes in environmental temperature were investigated for an environmental temperature range of 10°C to 30°C.The heart rate and respiratory rate in the mice increased in the cold environments and decreased in the hot environments. The correlations between the environmental temperature and heart rate, and environmental temperature and respiratory rate were significant at the 1% level. There were significant differences in analyses of variance on the heart rate and respiratory rate in mice exposed to various environmental temperatures. Also, they were significant at the 5% level among almost every environment which differed by 3°C and were significant at the 1 % level among each environment which differed by 6°C or more.The heat production in mice increased in the cold environments below 25°C, but it was almost same between 25°C and 30°C. The correlation between environmental temperature and heat production was significant at the 1 % level. It was recognized that there were differences in heat production among various environmental temperatures. They were significant at the 5% level between 10°C and 20°C, and 15°C and 25°C, but were not significant among the environments which differed by 5°C.