TY - JOUR T1 - Ca<sup>2+</sup> Mobilization Evoked by Chloroform in Madin-Darby Canine Kidney Cells JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 995 LP - 1001 VL - 292 IS - 3 AU - Chung-Ren Jan AU - Lee-Wei Chen AU - Ming-Wei Lin Y1 - 2000/03/01 UR - http://jpet.aspetjournals.org/content/292/3/995.abstract N2 - The effect of chloroform on Ca2+ mobilization in Madin-Darby canine kidney cells was examined by using Fura-2 as a Ca2+ probe. Chloroform (24–248 mM) concentration dependently increased intracellular Ca2+ concentration ([Ca2+]i). Ca2+ removal inhibited the Ca2+ signals evoked by 93 to 248 mM chloroform by reducing both the initial rise and the sustained phase. In Ca2+-free medium, pretreatment with 93 mM chloroform abolished the Ca2+ release induced by 1 μM thapsigargin, an endoplasmic reticulum Ca2+ pump inhibitor, and partially reduced the Ca2+ release induced by 2 μM carbonylcyanidem-chlorophenylhydrazone, a mitochondrial uncoupler. Pretreatment with carbonylcyanidem-chlorophenylhydrazone and thapsigargin to deplete the Ca2+ stores in mitochondria and the endoplasmic reticulum, respectively, only partially inhibited chloroform-induced Ca2+ release. This suggests that chloroform released Ca2+ from multiple internal pools. The addition of 3 mM Ca2+ increased [Ca2+]i after pretreatment with 93 mM chloroform in Ca2+-free medium. La3+ (1 mM) partially inhibited the [Ca2+]i increase induced by 93 mM chloroform. Chloroform (93 mM)-induced Ca2+ release was not altered when the formation of inositol-1,4,5-trisphosphate was abolished by U73122 (2 μM), a phospholipase C inhibitor, but was inhibited by 90% by inhibition of phospholipase A2 with 40 μM aristolochic acid. Collectively, we found that 93 mM chloroform increased [Ca2+]i in Madin-Darby canine kidney cells by releasing Ca2+ from multiple stores in a manner independent of the formation of inositol-1,4,5-trisphosphate, followed by Ca2+ entry from external medium. Other solvents, such as ethanol, methanol, and DMSO, did not affect the resting [Ca2+]i at a concentration of 248 mM. The American Society for Pharmacology and Experimental Therapeutics ER -