Myocardial developed tension and oxygen supply

¹ Department of Physiology, University of Oregon Medical School, Portland, Oregon

The isometric developed tension of rat's trabecula carnea was recorded, in vitro. The magnitude of the developed tension was observed to be directly a function of the partial pressure of oxygen in the aerating mixture. This activity reached a maximum at pO₂ values of 700 mm Hg. Fluctuations in the developed tension were noted during the 1st hr of the experiment; insignificant changes with noted exceptions occurred during the 2nd and 3rd hr. The data indicate that the mechanical response of the tissue is a function of both duration of the experiment and aerating gas mixture. The diflusion coefficient (D') of oxygen through the preparation was calculated. The results indicate that the D' value for heart muscle may be larger than that of skeletal muscle as determined by Krogh.

Key Words: myocardium and oxygen • contractility and oxygen • oxygen diffusion and heart muscle

Submitted on November 26, 1963