Phenylarsine oxide induces mitochondrial permeability transition, hypercontracture, and cardiac cell death.
The mitochondrial permeability transition (MPT) is implicated in cardiac reperfusion/reoxygenation injury. In isolated ventricular myocytes, the sulfhydryl (SH) group modifier and MPT inducer phenylarsine oxide (PAO) caused MPT, severe hypercontracture, and irreversible membrane injury associated with increased cytoplasmic free [Ca(2+)]. Removal of extracellular Ca(2+) or depletion of nonmitochondrial Ca(2+) pools did not prevent these effects, whereas the MPT inhibitor cyclosporin A was partially protective and the SH-reducing agent dithiothreitol fully protective. In permeabilized myocytes, PAO caused hypercontracture at much lower free [Ca(2+)] than in its absence. Thus PAO induced hypercontracture by both increasing myofibrillar Ca(2+) sensitivity and promoting mitochondrial Ca(2+) efflux during MPT. Hypercontracture did not directly cause irreversible membrane injury because lactate dehydrogenase (LDH) release was not prevented by abolishing hypercontracture with 2,3-butanedione monoxime. However, loading myocytes with the membrane-permeable Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA-AM) prevented PAO-induced LDH release, thus implicating the PAO-induced rise in cytoplasmic [Ca(2+)] as obligatory for irreversible membrane injury. In conclusion, PAO induces MPT and enhanced susceptibility to hypercontracture in isolated cardiac myocytes, both key features also implicated in cardiac reperfusion and reoxygenation injury.
Korge
P
P
Cardiovascular Research Laboratory, Departments of Medicine (Cardiology) and Physiology, University of California at Los Angeles School of Medicine, Los Angeles, California 90095-1760, USA.
Goldhaber
J I
JI
Weiss
J N
JN
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001152:Arsenicals / Q000494:pharmacology*; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects*; D002614:Chelating Agents / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006352:Heart Ventricles / Q000378:metabolism / Q000473:pathology; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism* / Q000473:pathology; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000473:pathology; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D009210:Myofibrils / Q000378:metabolism; D011817:Rabbits; D012508:Sarcolemma / Q000378:metabolism / Q000473:pathology
D001152:Arsenicals; D002614:Chelating Agents; D004791:Enzyme Inhibitors; C029341:oxophenylarsine; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D000255:Adenosine Triphosphate; D002118:Calcium; D004229:Dithiothreitol