Relationship between heart rate and metabolism in the hyrax (Procavia Capensis) and guineapig (Cavia porcellus)

The relationship between heart rate and metabolism was investigated in the hyrax Procavia capensis and the guineapig Cavia porcellus. In both animals a positive linear relationship was found described by Vo₂(ml 0₂(g.h)-¹)=0,003157 (HR) + 0,3678 for the hyrax and Vo₂(ml 0₂(g.h)-¹)=0,00757 (HR) -0,4914 in the guineapig. The response to lowered ambient temperature differs between the species, the guineapig increases metabolic rate and maintains body temperature while the hyrax allows body temperature to drop while the increase in metabolic rate is relatively small. It is postulated that this response by the hyrax is an energy conserving strategy.