The effect of previous diet on the metabolism of glucose by rat diaphragm.

It has been suggested by Lundbaek and Stevenson (1) and Gilmore and Samuels (2) that the metabolism of rat diaphragm in vitro can be influenced by the dietary history of the animal. Diaphragms obtained from rats maintained on either a high fat or high carbohydrate diet were incubated in a medium containing glucose. Both laboratories reported that less glucose was removed from the medium by diaphragms isolated from rats with high fat intakes. Lundbaek and Stevenson reported no significant differences between the two groups of animals in the amount of glycogen synthesized. Gilmore and Samuels, however, observed a net glycogen synthesis by diaphragms from the fat-fed animals, while the tissues from animals fed the carbohydrate diet contained less glycogen after incubation. The experiments reported here give some insight into this apparent disparity. Lactic acid and pyruvic acid analyses were also carried out and indicate differences in the metabolic activity of the tissues. Some experiments designed to suggest possible determinant factors producing this difference in metabolic activity are reported and discussed.