title: Lidocaine does not prevent the calcium paradox in rat hearts: a laser microprobe mass analysis (LAMMA) study.
abstract: The calcium paradox stands for the cell damage that occurs when isolated hearts are perfused with a Ca(2+)-free solution followed by perfusion with a Ca(2+)-containing solution. Although it is generally accepted that a massive Ca2+ influx during the Ca(2+)-repletion phase is responsible for the cell damage, there is no consensus about what makes the heart susceptible to the calcium paradox during the Ca(2+)-depletion phase. It has been suggested that the extent of the calcium paradox is primarily determined by accumulation of Na+ during Ca2+ depletion and a subsequent accumulation of Ca2+ via reverse Na(+)-Ca2+ exchange during Ca2+ repletion. According to another theory, weakening of intercalated disc junctions during Ca2+ depletion and contracture-mediated disruption of the cell membrane during Ca2+ repletion are responsible for the calcium paradox. In the present study we further investigated the possible role of Na+ in the development of the calcium paradox. During Ca2+ depletion, lidocaine was used to inhibit Na+ entry through the Na+ channels. Isolated rat hearts were perfused with Krebs Henseleit buffer (KH) containing 1.4 mM Ca2+ for 15 min, followed by 10 min of Ca(2+)-free perfusion and 10 min of reperfusion with Ca2+. In the treated group 0.1 mM lidocaine was present throughout the experiment. At the end of each experiment, Ca2+ cytochemistry was performed and the intracellular Ca2+ content was analyzed by laser microprobe mass analysis (LAMMA). The results show that during Ca2+ depletion, the intracellular Ca2+ content did not change significantly. Ca2+ repletion, however, gave rise to a full calcium paradox irrespective of the presence of lidocaine: massive cell damage and Ca2+ accumulation in the mitochondria. The results provide further evidence that intracellular Na+ accumulation during Ca2+ depletion is not involved in the occurrence of the calcium paradox.
authors.affiliation: Dept of Medicine and Chemistry, University of Antwep (UIA), Wilrijk-Antwerp, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Bakker
authors.forename: S
authors.initials: S
authors.lastname: De Nollin
authors.forename: L
authors.initials: L
authors.lastname: Van Vaeck
authors.forename: J
authors.initials: J
authors.lastname: Slezak
authors.forename: T
authors.initials: T
authors.lastname: Ravingerova
authors.forename: W
authors.initials: W
authors.lastname: Jacob
authors.forename: T J
authors.initials: TJ
authors.lastname: Ruigrok
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005260:Female; D008012:Lidocaine / Q000494:pharmacology*; D009206:Myocardium / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism
chemical_list: D008012:Lidocaine; D012964:Sodium; D002118:Calcium