Comparison of some metabolic parameters in the perfused and the incubated rat diaphragm muscle with diaphragm muscle in vivo.

1. A method is described for perfusing the rat diaphragm muscle. 2. The following parameters were compared in both perfused and non-perfused incubated preparations: water content, sorbitol space, rate of lactate production, and the concentrations of tissue glucose, pyruvate, lactate, hexose phosphate intermediates, ATP and AMP. No significant differences were found. 3. Significant differences, however, were found on comparison of the tissue kept in vitro with the tissue in vivo. Immediately after removal of the tissue from the animal, the concentrations of the hexose phosphates and ATP were found to be much higher than after incubation or perfusion, and the concentrations of free glucose and of AMP were much lower, possibly indicating that the capacity for oxidative phosphorylation of glucose is impaired in vitro because of hypoxia.