Progressive disruption of the plasma membrane during renal proximal tubule cellular injury

The goal of this study was to examine the progression of plasma membrane disruption during cell injury using rabbit renal proximal tubules (RPT). The results demonstrated that the plasma membrane became permeable to larger and larger molecules as anoxia proceeded. At least three distinctive phases of membrane disruption were differentiated during anoxia. In phases 1, 2, and 3, plasma membranes became permeable to propidium iodide (PI, molecular weight = 668), 3 kDa dextrans, and 70 kDa dextrans or lactate dehydrogenase (LDH, molecular weight = 140 kDa), respectively. Phase 1 was reversible by reoxygenation but not prevented by the glycine. Phase 2 was inhibited by glycine. Phase 3 was inhibited by several membrane-permeable homobifunctional crosslinkers, dimethyl-pimelimidate (DMP), ethylene-glycolbis(succinimidylsuccinate), and dithiobis(succinimidylpropionate), but not by the membrane-impermeable crosslinker dithiobis(sulfosuccinimidylpropionate). In addition, DMP decreased RPT LDH release produced by mitochondrial inhibition (antimycin A), an oxidant (t-butylhydroperoxide) and a nephrotoxicant that is metabolized to an electrophile (tetrafluoroethyl-L-cysteine). These results identify (1) different phases of plasma membrane damage with increasing permeability during cell injury, (2) the reversibility of phase 1, (3) the relative site of action of the cytoprotectant glycine (prevents phase 2), and (4) the protective effects of chemical crosslinkers in RPT cell death produced by different toxicants.