title: Cardioprotective effects of KB-R7943: a novel inhibitor of the reverse mode of Na+/Ca2+ exchanger.
abstract: The novel inhibitor of the reverse mode of the Na+/Ca2+ exchanger (NCE) KB-R7943 (KB) was tested in isolated rat cardiomyocytes exposed to 80 min of simulated ischemia [substrate-free anoxia, extracellular pH (pHo) of 6.4] and 15 min of reoxygenation (pHo 7.4). At pHo 6.4, 20 micromol/l KB was required for complete inhibition of the reverse mode of NCE. Treatment with 20 micromol/l KB only during anoxia did not influence the onset of rigor contracture and intracellular pH (pHi) (monitored with 2', 7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein) but significantly reduced the cytosolic accumulation of Ca2+ (monitored with fura 2) and Na+ (monitored with sodium-binding benzofuran isophthalate). During reoxygenation, cardiomyocytes developed hypercontracture. This was significantly reduced by anoxic KB treatment. To investigate this protection against reoxygenation-induced injury in the whole heart, we exposed Langendorff-perfused rat hearts to 110 min of anoxia (pHo 6.4) and 50 min of reoxygenation (pHo 7.4). Application of 20 micromol/l KB during anoxia significantly reduced the reoxygenation-induced enzyme release. We conclude that KB offers significant protection of cardiomyocytes against Ca2+ and Na+ overload during anoxia and hypercontracture or enzyme release on reoxygenation.
authors.affiliation: Physiologisches Institut, Justus-Liebig-Universität, D-35392 Giessen, Germany.
authors.forename: Y
authors.initials: Y
authors.lastname: Ladilov
authors.forename: S
authors.initials: S
authors.lastname: Haffner
authors.forename: C
authors.initials: C
authors.lastname: Balser-Schäfer
authors.forename: H
authors.initials: H
authors.lastname: Maxeiner
authors.forename: H M
authors.initials: HM
authors.lastname: Piper
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006321:Heart / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000378:metabolism; D066298:In Vitro Techniques; D008274:Magnesium / Q000378:metabolism; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D017202:Myocardial Ischemia / Q000503:physiopathology; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control; D009994:Osmolar Concentration; D010100:Oxygen / Q000009:adverse effects / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors*; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology; D013997:Time Factors
chemical_list: C101670:2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate; D019831:Sodium-Calcium Exchanger; D013890:Thiourea; D008274:Magnesium; D010100:Oxygen; D002118:Calcium