Mechanism of protective effects of Ca++ channel blockers on energy deprivation contracture in cultured ventricular myocytes.
To examine mechanisms of the protective effects of Ca++ channel blockers on energy deprivation contracture, we measured cystolic calcium ion concentration ([Ca++]i) (Indo-1 fluorescence), development of contracture (video motion detector) and ATP contents during exposure of cultured chick embryo ventricular cells to 1 mM cyanide (CN) and 20 mM 2-deoxyglucose (2-DG). The time periods required for [Ca++]i to reach 50% of [Ca++]i transient ([Ca++]i-50) and contracture were determined after exposure to 1) CN + 2-DG alone, 2) CN + 2-DG simultaneous with 1 microM verapamil (V-sim) and 3) verapamil followed by CN + 2-DG (V-pre). Time periods required to reach [Ca++]i-50 under these conditions were 4.2 +/- 0.4 min (CN + 2-DG alone), 3.8 +/- 0.4 min (NS vs. CN + 2-DG alone) (V-sim) and 6.4 +/- 1.1 min (P less than .05 vs. CN + 2-DG alone) (V-pre), respectively. Time periods required for contracture development were 4.4 +/- 0.3 min (CN + 2-DG alone), 4.4 +/- 0.6 min (NS vs. CN + 2-DG alone) (V-sim) and 9.3 +/- 1.2 min (P less than .05 vs. CN + 2-DG alone) (V-pre). Three minutes after metabolic inhibition, ATP contents declined from 32.3 +/- 0.7 nmol/mg of protein to 4.2 +/- 1.0 in CN + 2-DG alone, to 4.5 +/- 0.9 (NS vs. CN + 2-DG alone) with V-sim and to 8.3 +/- 2.2 (P less than .05 vs. CN + 2-DG alone) with V-pre.(ABSTRACT TRUNCATED AT 250 WORDS)
Kohmoto
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Department of Medicine, University of Utah School of Medicine, Salt Lake City.
Barry
W H
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D000255:Adenosine Triphosphate / Q000032:analysis; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002478:Cells, Cultured; D002642:Chick Embryo; D003486:Cyanides / Q000494:pharmacology; D003847:Deoxyglucose / Q000494:pharmacology; D004734:Energy Metabolism; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
D002121:Calcium Channel Blockers; D003486:Cyanides; D002110:Caffeine; D000255:Adenosine Triphosphate; D003847:Deoxyglucose; D012964:Sodium; D002118:Calcium