Effect of stretch on O₂ consumption of resting and active frog sartorius muscle

¹ Department of Physiology, College of Medicine, University of Iowa, Iowa City, Iowa

Oxygen consumption and resting and developed tension were measured simultaneously while the length of the muscle was increased by known increments. The Qo₂ of resting muscle increased about 1% for each 1% extension beyond the relaxed length. Both resting tension and length were directly related to Qo₂. In a stimulated muscle, Qo₂ and frequency of contraction showed a highly significant correlation. The Qo₂ of a stimulated muscle increased as the length and total tension (developed plus resting) increased. Neither Qo₂ nor the increment in Qo₂ above the resting level correlated significantly with developed tension. These latter findings differ from the results predicted from heat-liberation experiments. The results found here are not markedly different from those we found in heart muscle.