The Relationship Between Tissue Turnover and Metabolic Rate in Two Strains of Rats (Rattus norvegicus)

Stable isotope signatures show the rate of tissue turnover in two strains of rats (Rattus norvegicus) with different metabolic rates (MR). MR is hypothesized to be positively correlated with tissue turnover rate. If MR, a relatively simple measurement, can be correlated with tissue turnover, then this relationship could be used to study important ecological questions, such as those involving migration and seasonally available nutrient sources. Here, oxygen consumption was used to measure MR. After a diet switch, the changing signatures of carbon and nitrogen from whole blood were mathematically modeled. The mass and MRs were significantly different between strains, but half-life and the metabolic component of turnover (m) were not. No significant correlation was found between MR and m between the strains. Results suggest that within a species with a range of MRs, tissue turnover occurs at relatively the same rate.