Volume regulation and plasma membrane injury in aerobic, anaerobic, and XXXX in vitro. Effects of osmotic cell swelling on plasma membrane integrity.

@entity7493 @entity296 @entity63 @entity2421 @entity1162
The relationship between cell swelling and plasma membrane disruption has been evaluated in thin @entity296 incubated in oxygenated or anoxic Krebs-Ringer phosphate media. Electron microscopy and measurements of inulin-diffusible space were used to monitor plasma membrane integrity. Inulin is excluded from the intracellular space of intact cells; therefore, an increase in tissue inulin content is an excellent marker of loss of plasma membrane integrity. Cell volume was increased during exposure of aerobic slices to @entity2421 media, but the inulin-diffusible space was not increased and electron micrographs showed no detectable plasma membrane alterations. Likewise, during @entity1162 , no evidence of plasma membrane damage was observed. Incubation in anoxic @entity2421 media for 60 minutes resulted in a larger increase in cell volume than under aerobic conditions, but plasma membrane integrity was maintained. @entity2421 (300 minutes) produced no further change in tissue water, but the inulin-diffusible space was increased and electron micrographs revealed breaks in the plasma membranes primarily in association with large subsarcolemmal blebs. Likewise, @entity296 incubated in isotonic anoxic media for 240 minutes and @entity2421 anoxic media for 60 minutes had an increased inulin-diffusible space and the ultrastructural appearance was similar. This ultrastructural appearance is indistinguishable from that observed in myocytes lethally injured by @entity63 . Measurements of tissue osmolarity during total @entity63 showed that osmotically induced cell swelling could occur in @entity63 prior to the onset of plasma membrane disruption. Our results indicate that cell swelling per se is incapable of rupturing plasma membranes; however, after prolonged periods of @entity7493 , the plasma membrane or its cytoskeletal scaffold become injured, which allows the membrane to rupture if the cell is swollen, as might occur during @entity63 or reperfusion.
