title: Ca(2+) mobilization evoked by chloroform in Madin-Darby canine kidney cells.
abstract: The effect of chloroform on Ca(2+) mobilization in Madin-Darby canine kidney cells was examined by using Fura-2 as a Ca(2+) probe. Chloroform (24-248 mM) concentration dependently increased intracellular Ca(2+) concentration ([Ca(2+)](i)). Ca(2+) removal inhibited the Ca(2+) signals evoked by 93 to 248 mM chloroform by reducing both the initial rise and the sustained phase. In Ca(2+)-free medium, pretreatment with 93 mM chloroform abolished the Ca(2+) release induced by 1 microM thapsigargin, an endoplasmic reticulum Ca(2+) pump inhibitor, and partially reduced the Ca(2+) release induced by 2 microM carbonylcyanide m-chlorophenylhydrazone, a mitochondrial uncoupler. Pretreatment with carbonylcyanide m-chlorophenylhydrazone and thapsigargin to deplete the Ca(2+) stores in mitochondria and the endoplasmic reticulum, respectively, only partially inhibited chloroform-induced Ca(2+) release. This suggests that chloroform released Ca(2+) from multiple internal pools. The addition of 3 mM Ca(2+) increased [Ca(2+)](i) after pretreatment with 93 mM chloroform in Ca(2+)-free medium. La(3+) (1 mM) partially inhibited the [Ca(2+)](i) increase induced by 93 mM chloroform. Chloroform (93 mM)-induced Ca(2+) release was not altered when the formation of inositol-1,4,5-trisphosphate was abolished by U73122 (2 microM), a phospholipase C inhibitor, but was inhibited by 90% by inhibition of phospholipase A(2) with 40 microM aristolochic acid. Collectively, we found that 93 mM chloroform increased [Ca(2+)](i) in Madin-Darby canine kidney cells by releasing Ca(2+) from multiple stores in a manner independent of the formation of inositol-1,4,5-trisphosphate, followed by Ca(2+) entry from external medium. Other solvents, such as ethanol, methanol, and DMSO, did not affect the resting [Ca(2+)](i) at a concentration of 248 mM.
authors.affiliation: Department of Medical Education, Veterans General Hospital-Kaohsiung, Taiwan. crjan@isca.vghks.gov.tw
authors.forename: C R
authors.initials: CR
authors.lastname: Jan
authors.forename: L W
authors.initials: LW
authors.lastname: Chen
authors.forename: M W
authors.initials: MW
authors.lastname: Lin
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002460:Cell Line; D002725:Chloroform / Q000633:toxicity*; D004285:Dogs; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D019284:Thapsigargin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
chemical_list: D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D019284:Thapsigargin; D002725:Chloroform; D000255:Adenosine Triphosphate; D010741:Phospholipases A; D010738:Type C Phospholipases; D002118:Calcium