Influence of Microorganisms on Oxygen Consumption, Carbon Dioxide Production and Colonic Temperature of Rats ,

Abstract

The O2 consumption and CO2 production by germfree rats and their colonic temperature are significantly lower than those of conventionalized rats; the respiratory quotient (RQ) is not different. When germfree rats are monocontaminated with Clostridium welchii or Bacteroides sp. there were no changes in O2 consumption or CO2 production. When Escherichia coli (a facultative anaerobe) was the monocontaminant, colonic temperature did not change but there were prompt and parallel rises in O2 consumption and CO2 production to levels close to those of conventionalized rats. The changes in metabolic rate lagged behind the increase in viable bacteria in the feces. The feeding of large quantities of heat-killed E. coli to germfree rats did not change their O2 consumption, CO2 production or colonic temperature. Serum protein-bound iodine and serum thyroxine iodine levels were similar in the germfree, conventionalized, E. coli and Bacteroides sp. rats. When neomycin was given to rats harboring Bacteroides sp., E. coli and Proteus sp., the numbers of these bacteria were reduced and oxygen consumption and carbon dioxide production fell; colonic temperature did not change. It appears that the bacteria and mechanisms involved for the metabolic and colonic temperature changes noted may be different.