A dual mechanism of cytoprotection afforded by M-LDH in embryonic heart H9C2 cells.
Muscle form of lactate dehydrogenase (M-LDH), a minor LDH form in cardiomyocytes, physically interacts with ATP-sensitive K+ (K ATP) channel-forming subunits. Here, we have shown that expression of 193gly-M-LDH, an inactive mutant of M-LDH, inhibit regulation of the K ATP channels activity by LDH substrates in embryonic rat heart H9C2 cells. In cells expressing 193gly-M-LDH chemical hypoxia has failed to activate K ATP channels. The similar results were obtained in H9C2 cells expressing Kir6.2AFA, a mutant form of Kir6.2 with largely decreased K+ conductance. Kir6.2AFA has slightly, but significantly, reduced cellular survival under chemical hypoxia while the deleterious effect of 193gly-M-LDH was significantly more pronounced. The levels of total and subsarcolemmal ATP in H9C2 cells were not affected by Kir6.2AFA, but the expression of 193gly-M-LDH led to lower levels of subsarcolemmal ATP during chemical hypoxia. We conclude that M-LDH regulates both the channel activity and the levels of subsarcolemmal ATP and that both mechanism contribute to the M-LDH-mediated cytoprotection.
Jovanović
Sofija
S
Division of Medical Sciences, Centre for Cardiovascular and Lung Biology, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY Scotland, UK.
Du
Qingyou
Q
Sukhodub
Andriy
A
Jovanović
Aleksandar
A
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002470:Cell Survival; D017931:DNA Primers / Q000235:genetics; D004622:Embryo, Mammalian; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000201:enzymology*; D018408:Patch-Clamp Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000099161:Kcnj11 Channel
D000255:Adenosine Triphosphate; D017931:DNA Primers; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase; D024661:Potassium Channels, Inwardly Rectifying; D012333:RNA, Messenger; D011994:Recombinant Proteins; D000099161:Kcnj11 Channel