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Comparative analysis of the bioenergetic parameters of adult rat cardiomyocytes (CM) and HL-1 cells with very different structure but similar cardiac phenotype was carried out with the aim of revealing the importance of the cell structure for regulation of its energy fluxes. Confocal microscopic analysis showed very different mitochondrial arrangement in these cells. The cytochrome content per milligram of cell protein was decreased in HL-1 cells by a factor of 7 compared with CM. In parallel, the respiratory chain complex activities were decreased by 4-8 times in the HL-1 cells. On the contrary, the activities of glycolytic enzymes, hexokinase (HK), and pyruvate kinase (PK) were increased in HL-1 cells, and these cells effectively transformed glucose into lactate. At the same time, the creatine kinase (CK) activity was significantly decreased in HL-1 cells. In conclusion, the results of this study comply with the assumption that in contrast to CM in which oxidative phosphorylation is a predominant provider of ATP and the CK system is a main carrier of energy from mitochondria to ATPases, in HL-1 cells the energy metabolism is based mostly on the glycolytic reactions coupled to oxidative phosphorylation through HK. Key words: cardiomyocytes, HL-1 cells, respiration, cytochromes, glycolysis, energy metabolism. On a effectue chez des rats adultes une analyse comparee des parametres bioenergetique des cardiomyocytes (CM) et des cellules HL-1, qui ont une structure tres differente mais un phenotype cardiaque similaire, pour montrer l'importance de la structure cellulaire pour la regulation de ses flux energetiques. L'analyse par microscopie confocale a montre une repartition mitochondriale differente dans ces cellules. La teneur en cytochromes par mg de proteine cellulaire a diminue d'un facteur 7 dans les cellules HL-1 par comparaison a celles des CM. Parallelement, les activites complexes de la chaine respiratoire ont diminue de 4 a 8 fois dans les cellules HL-1. En revanche, les activites des enzymes glycolytiques, hexokinase (HK) et pyruvate kinase (PK), ont augmente dans les cellules HL-1, lesquelles ont transforme efficacement le glucose en lactate. L'activite de la creatine kinase (CK) des cellules HL-1 a aussi diminue significativement. En conclusion, les resultats de cette etude viennent etayer a l'hypothese que, contrairement aux CM ou la phosphorylation oxydative est un fournisseur important d'ATP et le systeme CK, le principal transporteur d'energie des mitochondries vers les ATPases, dans les cellules HL-1, le metabolisme energetique repose principalement sur les reactions glycolytiques couplees a la phosphorylation oxydative par l'HK. Mots-cles : cardiomyocytes, cellules HL-1, respiration, cytochromes, glycolyse, metabolisme energetique. [Traduit par la Redaction], Introduction Studies of energy metabolism in muscle cells have led to a conclusion that the metabolic compartmentalization and mechanisms of regulation of oxidative phosphorylation are system-level properties giving rise to [...]

Energy metabolism in gastrobiopsy specimens of the antral and corpus mucosa, treated with saponin to permeabilize the cells, was studied in patients with gastric diseases. The results show twice lower oxidative capacity in the antral mucosa than in the corpus mucosa and the relative deficiency of antral mitochondria in complex I. The mucosal cells expressed mitochondrial and cytosolic isoforms of creatine kinase and adenylate kinase (AK). Creatine (20 mM) and AMP (2 mM) markedly stimulated mitochondrial respiration in the presence of submaximal ADP or ATP concentrations, and creatine reduced apparent [K.sub.m] for ADP in stimulation of respiration, which indicates the functional coupling of mitochondrial kinases to oxidative phosphorylation. Addition of exogenous cytochrome c increased ADP-dependent respiration, and the large-scale cytochrome c effect ([greater than or equal to] 20%) was associated with suppressed stimulation of respiration by creatine and AMP in the mucosal preparations. These results point to the impaired mitochondrial outer membrane, probably attributed to the pathogenic effects of Helicobacter pylori. Compared with the corpus mucosa, the antral mucosa exhibited greater sensitivity to such type of injury as the prevalence of the large-scale cytochrome c effect was twice higher among the latter specimens. Active chronic gastritis was associated with decreased respiratory capacity of the corpus mucosa but with its increase in the antral mucosa. In conclusion, human gastric mucosal cells express the mitochondrial and cytosolic isoforms of CK and AK participating in intracellular energy transfer systems. Gastric mucosa disease is associated with the altered functions of these systems and oxidative phosphorylation. human stomach mucosa; corpus; antrum

The cellular energy metabolism in human musculus gluteus medius (MGM) under normal conditions and hip osteoarthritis (OA) was explored. The functions of oxidative phosphorylation and energy transport systems were analyzed in permeabilized (skinned) muscle fibers by oxygraphy, in relation to myosin heavy chain (MHC) isoform distribution profile analyzed by SDS-PAGE, and to creatine kinase (CK) and adenylate kinase (AK) activities measured spectrophotometrically in the intact muscle. The results revealed high apparent Km for ADP in regulation of respiration that decreased after addition of creatine in MGM of traumatic patients (controls). OA was associated with increased sensitivity of mitochondrial respiration to ADP, decreased total activities of AK and CK with major reduction in mi-CK fraction, and attenuated effect of creatine on apparent [K.sub.m] for ADP compared with control group. It also included a complete loss of type II fibers in a subgroup of patients with the severest disease grade. It is concluded that energy metabolism in MGM cells is organized into functional complexes of mitochondria and ATPases. It is suggested that because of degenerative remodeling occurring during development of OA, these complexes become structurally and functionally impaired, which results in increased access of exogenous ADP to mitochondria and dysfunction of CK-phosphotransfer system. musculus gluteus medius; myosin heavy chains; mitochondrial respiration; energy transfer

The influence of sarcoplasmic reticulum function in determining the atrioventricular contractile differences was determined through comparison of the contractile characteristics of rat atrial and ventricular trabeculae. Results have shown that the fast and efficient CK-supported SR calcium uptake in combination of slow calcium release were the main modulator of the shorter time course and lower tension development in rat intact atrial myocardium in contrast with ventricular myocardium.