Effect of t-butyl hydroperoxide on Ca2+ movement in PC12 pheochromocytoma cells.
The effect of the oxidant t-butyl hydroperoxide on intracellular free levels of Ca2+ ([Ca2+]i) in PC12 pheochromocytoma cells was examined by using fura-2 as a fluorescent dye. t-Butyl hydroperoxide induced an increase in [Ca2+]i in a concentration-dependent fashion between 50-250 microM with an EC50 of 100 microM. The [Ca2+]i signal consisted of a slow rise and a sustained phase. The response was decreased by 65% by removal of extracellular Ca2+. In Ca(2+)-free medium, pretreatment with 1 microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor) abolished 150 microM t-butyl hydroperoxide-induced [Ca2+]i increase, and conversely, pretreatment with t-butyl hydroperoxide abrogated thapsigargin-induced [Ca2+]i increase. The 150 microM t-butyl hydroperoxide-induced [Ca2+]i increase in Ca2+ medium was reduced by 42 +/- 5% by pretreatment with 0.1 microM nicardipine but not by 10 microM verapamil, nifedipine, nimodipine or diltiazem, or by 50 microM La3+ or Ni2+. Pretreatment with 10 microM t-butyl hydroperoxide for 40 min did not affect 10 microM ATP-induced [Ca2+]i increase. Together, the results show that t-butyl hydroperoxide induced significant [Ca2+]i increase in PC12 cells by causing store Ca2+ release from the thapsigargin-sensitive endoplasmic reticulum pool in an inositol 1,4,5-trisphosphate-independent manner and by inducing Ca2+ influx via a nicardipine-sensitive pathway.
Lu
Cheng-Hsien
CH
Department of Neurology, Chang Gung Memorial Hospital-Kaohsiung, Kaohsiung, Taiwan, Republic of China.
Su
Warren
W
Lo
Yuk-Keung
YK
Chen
Wei-Chung
WC
Chang
Wen-Neng
WN
Wang
Jue-Long
JL
Tsai
Yu-Chun
YC
Lee
Ping-Yu
PY
Jan
Chung-Ren
CR
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D005456:Fluorescent Dyes; D016257:Fura-2; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D016716:PC12 Cells; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020122:tert-Butylhydroperoxide / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D004791:Enzyme Inhibitors; D004963:Estrenes; D005456:Fluorescent Dyes; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D020122:tert-Butylhydroperoxide; D010738:Type C Phospholipases; D002118:Calcium; D016257:Fura-2