Seppet 2005 Mol Cell Biochem
|Seppet E, Eimre M, Peet N, Paju K, Orlova E, Ress M, Kovask S, Piirsoo A, Saks VA, Gellerich FN, Zierz S, Seppet EK (2005) Compartmentation of energy metabolism in atrial myocardium of patients undergoing cardiac surgery. Mol Cell Biochem 270:49-61.|
Abstract: The parameters of oxidative phosphorylation and its interaction with creatine kinase (CK)- and adenylate kinase (AK)-phosphotransfer networks in situ were studied in skinned atrial fibers from 59 patients undergoing coronary artery bypass surgery, valve replacement/correction and atrial septal defect correction. In atria, the mitochondrial CK and AK are effectively coupled to oxidative phosphorylation, the MM-CK is coupled to ATPases and there exists a direct transfer of adenine nucleotides between mitochondria and ATPases. Elimination of cytoplasmic ADP with exogenous pyruvate kinase was not associated with a blockade of the stimulatory effects of creatine and AMP on respiration, neither could it abolish the coupling of MM-CK to ATPases and direct transfer of adenine nucleotides. Thus, atrial energy metabolism is compartmentalized so that mitochondria form functional complexes with adjacent ATPases. These complexes isolate a part of cellular adenine nucleotides from their cytoplasmic pool for participating in energy transfer via CK- and AK-networks, and/or direct exchange. Compared to atria in sinus rhythm, the fibrillating atria were larger and exhibited increased succinate-dependent respiration relative to glutamate-dependent respiration and augmented proton leak. Thus, alterations in mitochondrial oxidative phosphorylation may contribute to pathogenesis of atrial fibrillation.
• Keywords: Skinned fibers, Human myocardium, Mitochondria, Oxidative phosphorylation, Phosphotransfer networks
Organism: Human Tissue;cell: Heart Preparation: Permeabilized tissue
Coupling state: OXPHOS