THE ROLE OF GLUTATHIONE AND PROTEIN THIOLS IN CBRCL3-INDUCED CYTOTOXICITY IN ISOLATED RAT HEPATOCYTES

The role of glutathione (GSH) and protein thiols in the pathobiochemic al process of CBrCl3 cytotoxicity was investigated in isolated hepatoc ytes. Administration of 0.5, 1.0 and 1.5 mmol/l CBrCl3 affected cellul ar viability as assessed by trypan blue exclusion, release of lactate dehydrogenase and loss of intracellular potassium in a dose-dependent manner. Intracellular glutathione and the capacity to reduce (4,5-dime thylthiazolyl-2-)-2,5-diphenyltetrazolium bromide (MTT, thiazolyl blue ) decreased almost independently of the CBrCl3 concentration. Protein thiols were not markedly oxidized in the presence of CBrC1(3). However , compromising cellular defence mechanisms by either inhibition of glu tathione regeneration or depletion of glutathione enhanced the cytotox icity of CBrCl3 and induced a loss of protein thiols in the late phase of cellular injury. Under these conditions the thiol-dependent Na+,K(A)TPase revealed high sensitivity towards CBrCl3. Thus, glutathione p roved to exert effective cytoprotection, and sulfhydryl groups of part icular proteins were supposed to be an important target of radical att ack.