Abstract
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)
JPET articles become freely available 12 months after publication, and remain freely available for 5 years.Non-open access articles that fall outside this five year window are available only to institutional subscribers and current ASPET members, or through the article purchase feature at the bottom of the page.
|