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Ca 2+ antagonists inhibit DNA fragmentation and toxic cell death induced by acetaminophen 1
Author(s) -
Ray Sidhartha D.,
Kamendulis Lisa M.,
Gurule Mark W.,
Yorkin Robert D.,
Corcoran George B.
Publication year - 1993
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.7.5.8462787
Subject(s) - fragmentation (computing) , chemistry , dna fragmentation , acetaminophen , dna , programmed cell death , pharmacology , apoptosis , biology , biochemistry , ecology
Ca 2+ accumulates in the nucleus and DNA undergoes enzymatic cleavage into internucleosomelength fragments before acetaminophen and dimethylnitrosamine produce hepatic necrosis in vivo and toxic cell death in vitro. However, Ca 2+ ‐endonuclease fragmentation of DNA is characteristic of apoptosis, a type of cell death considered biochemically and functionally distinct from toxic cell death. The present studies investigate DNA fragmentation as a critical event in toxic cell death by testing whether the Ca 2+ ‐calmodulin antagonist chlorpromazine and the Ca 2+ channel blocker verapamil prevent acetaminophen‐induced hepatic necrosis by inhibiting Ca 2+ deregulation and DNA damage. Acetaminophen overdose in mice produced accumulation of Ca 2+ in the nucleus (358% of control) and fragmentation of DNA (250% of control) by 6 h, with peak release of ALT occurring at 12–24 h (58,000 U/l). Pretreatment with chlorpromazine prevented increases in nuclear Ca 2+ and DNA fragmentation and nearly abolished biochemical evidence of toxic cell death. Verapamil pretreatment also decreased Ca 2+ accumulation and DNA damage while attenuating liver injury. The Ca 2+ antagonists did not protect against toxic cell death through hypothermia because neither produced the delay in toxicity that is customarily associated with hypothermia. Nor did chlorpromazine or verapamil protect through inhibiting acetaminophen bioactivation. Chlorpromazine failed to diminish glutathione depletion in whole liver and isolated nuclei. Verapamil (250 μM) also failed to alter glutathione depletion in whole liver and had no effect on acetaminophenglutathione adduct formation by mouse liver microsomes and by cultured mouse hepatocytes. Collectively, these results support the hypothesis that Ca 2+ ‐induced DNA fragmentation plays a significant role in cell necrosis produced by acetaminophen and may contribute to toxic cell death caused by other alkylating hepatotoxins.— Ray, S. D., Kamendulis, L. M., Gurule, M. W., Yoridn, R. D., Corcoran, G. B. Ca 2+ antagonists inhibit DNA fragmentation and toxic cell death induced by acetaminophen. FASEB J. 7: 453‐463; 1993.