A quantitative fluorescent microscopy system was developed to characterize, in real time, the effects of supraphysiological temperatures between 37 degrees and 70 degrees C on the plasma membrane of mouse 3T3 fibroblasts and isolated rat skeletal muscle cells. Membrane permeability was assessed by monitoring the leakage as a function of time of the fluorescent membrane integrity probe calcein. The kinetics of dye leakage increased with increasing temperature in both the 3T3 fibroblasts and the skeletal muscle cells. Analytical solutions derived from a two-compartment transport model showed that, for both cell types, a time-dependent permeability assumption provided a statistically better fit of the model predictions to the data than a constant permeability assumption. This finding suggests that the plasma membrane integrity is continuously being compromised while cells are subjected to supraphysiological temperatures.
Bibliographical noteFunding Information:
The authors thank Mr. William Thorpe for his excellent technical help. This research was partially funded by the Shriners Hospitals for Crippled Children, the Electric Power Research Institute, Empire State Electric Energy Research Co., Northeast Utilities Service Co., Pacific Gas and Electric Co., Public Service Co. of Oklahoma, The Public Service Electric and Gas Co. of New Jersey, The Muscular Dystrophy Association, and a Career Development Award (to R.M.E.) from the Crohn's and Colitis Foundation of America. The responsibility of the research rests solely with the authors.