Oxygen consumption of muscles from ob/ob and Ay/a strains of obese mice

Oxygen consumption was measured in the in vitro preparations of soleus, extensor digitorum longus, gracilis, and diaphragm muscles from young ob/ob obese mice. In young Ay/a obese mice, similar measurements were made with in vitro preparations of soleus, gracilis, and diaphragm muscles. These young obese mice were heavier than their nonobese littermates. Muscle weights were similar in obese and nonobese mice. In the Ay/a obese mice, values of muscle oxygen consumption were similar to those found in the a/a nonobese littermates. This correlates well with other known information about the Ay/a variety of obesity. In the ob/ob obese mice, values of oxygen consumption in the gracilis and diaphragm muscle preparations were lower than those in nonobese littermates. These data indicate that some muscles in the ob/ob obese mice contribute to the depressed whole animal oxygen consumption by virtue of defective oxidative metabolism. The data also indicate that the tissue defects are very different in various types of obese animal models. This probably is also true for different types of human obesity.