DYNAMICS OF CELL-MEMBRANE PERMEABILITY CHANGES AT SUPRAPHYSIOLOGICAL TEMPERATURES

A quantitative fluorescent microscopy system was developed to characte rize, in real time, the effects of supraphysiological temperatures bet ween 37 degrees and 70 degrees C on the plasma membrane of mouse 3T3 f ibroblasts and isolated rat skeletal muscle cells. Membrane permeabili ty was assessed by monitoring the leakage as a function of time of the fluorescent membrane integrity probe calcein. The kinetics of dye lea kage increased with increasing temperature in both the 3T3 fibroblasts and the skeletal muscle cells. Analytical solutions derived from a tw o-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 ass umption. This finding suggests that the plasma membrane integrity is c ontinuously being compromised while cells are subjected to supraphysio logical temperatures.