[The effect of Ca(2+)-induced opening of cyclosporine-sensitive pore on the oxygen consumption and functional state of rat liver mitochondria].
The effect of Ca(2+)-induced opening of cyclosporine-sensitive pore (mitochondrial permeability transition pore, MPTP) on the oxygen consumption and mitochondrial functional state was studied in the rat liver mitochondria. It was shown that, with the use of glutamate as oxidation substrate, in the absence of depolarization MPTP opening results in the increase of steady state respiration rate because of the activation of cyclosporine-sensitive Ca2+/H(+)-exchange and Ca2+ cycling, which was supported by the simultaneous work of MPTP and Ca(2+)-uniporter. With the aid of selective blockers, cyclosporine A and ruthenium red, it was shown that MPTP and Ca(2+)-uniporter contribute equally to the Ca(2+)-cycling and mitochondrial respiration. It was shown that bioenergetic effects of MPTP opening under steady state conditions (increase in the oxygen consumption rate under substrate oxidation without ADP, decrease in respiratory control ratio as well as the effectiveness of ATP synthesis, P/O) are close to the functional alterations, which result from the increase of endogenous proton conductance of mitochondrial membrane. Uncoupling effect of MPTP opening, by itself, had no effect on phosphorylation rate, which remains relatively stable because the fall of P/O is compensated by the activation of respiratory chain and the increase in the rate of state 3 respiration. It was concluded that under physiologically normal conditions MPTP might function as the endogenous mechanism of mild uncoupling of respiratory chain.
O V
OV
Akopova
V I
VI
Nosar'
I N
IN
Man'kovskaia
V F
VF
Sagach
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000818:Animals; D021461:Animals, Outbred Strains; D017920:Antiporters / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016572:Cyclosporine / Q000494:pharmacology*; D004579:Electron Transport / Q000187:drug effects; D018698:Glutamic Acid / Q000378:metabolism; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000083162:Mitochondrial Permeability Transition Pore; D010085:Oxidative Phosphorylation / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects*; D051381:Rats; D012430:Ruthenium Red / Q000494:pharmacology
D017920:Antiporters; D015220:Calcium Channels; D027682:Cation Transport Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; C027614:calcium-hydrogen antiporters; C034703:mitochondrial calcium uniporter; D012430:Ruthenium Red; D018698:Glutamic Acid; D000244:Adenosine Diphosphate; D016572:Cyclosporine; D000255:Adenosine Triphosphate; D002118:Calcium