Specific up-regulation of mitochondrial F0F1-ATPase activity after short episodes of atrial fibrillation in sheep.
BACKGROUND
Ventricular fibrillation induced by either digitalis intoxication or electrical stimulation is reported to alter myocardial energy by impairing the sarcolemmal Na,K-ATPase or the receptor for digitalis and the mitochondrial ATPase synthase or F0F1-ATPase. However, little is known about these membrane functions during atrial fibrillation (AF).


RESULTS
We analyzed the effects of electrically induced AF on biochemical activities of atrial F0F1-ATPase and Na,K-ATPase in sheep. A group of six sheep was subjected to direct short electrical stimulation of the right atrium to induce AF. Sham-operated sheep served as a control group. Microsomal and mitochondrial membranes of atrial muscle were isolated and tested for enzymatic activity. All paced sheep developed multiple episodes of sustained AF, with a mean total duration of 110 minutes over a 2-hour period. Data showed that short-term pacing-induced AF significantly activated membrane F0F1-ATPase activity (P < 0.05) without changes in cytochrome-c oxidase activity, Na,K-ATPase activity, ouabain sensitivity, and alpha1-subunit expression.


CONCLUSIONS
Specific activation of F0F1-ATPase activity is an early molecular consequence of sustained AF in sheep.
Barbey
O
O
Laboratoire de Recherche Cardiologique, University of Marseille, School of Medicine, Centre Hospitalo-Universitaire Nord, France.
Pierre
S
S
Duran
M J
MJ
Sennoune
S
S
Lévy
S
S
Maixent
J M
JM
D000818:Animals; D001281:Atrial Fibrillation / Q000201:enzymology* / Q000209:etiology; D015415:Biomarkers; D015153:Blotting, Western; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004558:Electric Stimulation / Q000009:adverse effects; D003576:Electron Transport Complex IV / Q000037:antagonists & inhibitors / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors; D006325:Heart Atria / Q000201:enzymology*; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology; D008929:Mitochondria, Heart / Q000187:drug effects / Q000201:enzymology*; D010042:Ouabain; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012756:Sheep; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism; D015854:Up-Regulation
D015415:Biomarkers; D004791:Enzyme Inhibitors; D010042:Ouabain; D003576:Electron Transport Complex IV; D006180:Proton-Translocating ATPases; D000254:Sodium-Potassium-Exchanging ATPase