[Changes in carbohydrate metabolism and efficiency of hypoglycemic drugs related to the light dark cycle in rats. A study on stimulated diaphragm (author's transl)].

A study of glucose uptake and lactate release was performed on isolated diaphragm stimulated regularly by an electric device. This stimulated model is much more sensitive than the motionless diaphragm preparation in the Warburg apparatus. The diaphragms take up twice as much glucose and release one and a half times more lactate during summer than during winter. This increase relates to lighting conditions. It is suppressed even during summer, if rats are maintained in darkness for 15 days before the experiment, other factors remaining unchanged. Several antidiabetic drugs (insulin, metformin, phenformin, buformin), active on the stimulated diaphragm, have their effects reduced or suppressed when animals are exposed to intense light; they regain their effect even during summer, if the animals are kept in the dark. The mechanism and practical implication of these findings are discussed.