title: Na+/H+ exchanger inhibitor cariporide attenuates the mitochondrial Ca2+ overload and PTP opening.
abstract: The Na(+)/H(+) exchanger (NHE) inhibitor cariporide has a cardioprotective effect in various animal models of myocardial ischemia-reperfusion. Recent studies have suggested that cariporide interacts with mitochondrial Ca(2+) overload and the mitochondrial permeability transition (MPT); however, the precise mechanisms remain unclear. Therefore, we examined whether cariporide affects mitochondrial Ca(2+) overload and MPT. Isolated adult rat ventricular myocytes were used to study the effects of cariporide on hypercontracture induced by ouabain or phenylarsine oxide (PAO). Mitochondrial Ca(2+) concentration ([Ca(2+)](m)) and the mitochondrial membrane potential (DeltaPsi(m)) were measured by loading myocytes with rhod-2 and JC-1, respectively. We also examined the effect of cariporide on the MPT using tetramethylrhodamine methyl ester (TMRM) and oxidative stress generated by laser illumination. Cariporide (1 microM) prevented ouabain-induced hypercontracture (from 40 +/- 2 to 24 +/- 2%, P < 0.05) and significantly attenuated ouabain-induced [Ca(2+)](m) overload (from 149 +/- 6 to 121 +/- 5% of the baseline value, P < 0.05) but did not affect DeltaPsi(m). These results indicate that cariporide attenuates the [Ca(2+)](m) overload without the accompanying depolarization of DeltaPsi(m). Moreover, cariporide increased the time taken to induce the MPT (from 79 +/- 11 to 137 +/- 20 s, P < 0.05) and also attenuated PAO-induced hypercontracture (from 59 +/- 3 to 50 +/- 4%, P < 0.05). Our data indicate that cariporide attenuates [Ca(2+)](m) overload and MPT. Thus these effects might potentially contribute to the mechanisms of cardioprotection afforded by NHE inhibitors.
authors: Department of Pediatrics, Yamanashi University School of Medicine, Yamanashi, Japan.
authors: Takako
authors: T
authors: Toda
authors: Toshie
authors: T
authors: Kadono
authors: Minako
authors: M
authors: Hoshiai
authors: Yu
authors: Y
authors: Eguchi
authors: Shinpei
authors: S
authors: Nakazawa
authors: Hiroe
authors: H
authors: Nakazawa
authors: Naoko
authors: N
authors: Higashijima
authors: Hideyuki
authors: H
authors: Ishida
mesh_terms: D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D001152:Arsenicals / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002316:Cardiotonic Agents / Q000494:pharmacology; D003652:Decanoic Acids / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D006146:Guanidines / Q000494:pharmacology*; D006352:Heart Ventricles / Q000187:drug effects / Q000378:metabolism; D006880:Hydroxy Acids / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000187:drug effects* / Q000378:metabolism; D000083162:Mitochondrial Permeability Transition Pore; D009200:Myocardial Contraction / Q000187:drug effects; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013450:Sulfones / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D000889:Anti-Arrhythmia Agents; D001152:Arsenicals; D002316:Cardiotonic Agents; D003652:Decanoic Acids; D006146:Guanidines; D006880:Hydroxy Acids; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D017923:Sodium-Hydrogen Exchangers; D013450:Sulfones; C117780:mitochondrial K(ATP) channel; C029341:oxophenylarsine; D010042:Ouabain; C052853:5-hydroxydecanoic acid; C093373:cariporide; D012964:Sodium; D005905:Glyburide; D002118:Calcium