Effect of antihypertensive agents - captopril and nifedipine - on the functional properties of rat heart mitochondria.

Objectives: Investigation of acute effect on cellular bioenergetics provides the opportunity to characterize the possible adverse effects of drugs more comprehensively. This study aimed to investigate the changes in biochemical and biophysical properties of heart mitochondria induced by captopril and nifedipine antihypertensive treatment.

Materials And Methods: Male, 12-week-old Wistar rats in two experimental models (in vivo and in vitro) were used.

Mitochondrial function in heart and kidney of spontaneously hypertensive rats: influence of captopril treatment.

Effect of captopril treatment on capability of heart and kidney mitochondria to produce ATP was investigated in spontaneously hypertensive rats (SHR). Heart mitochondria from SHR responded to hypertension with tendency to compensate the elevated energy demands of cardiac cells by moderate increase in mitochondrial Mg2+-ATPase activity, membrane fluidity (MF) and in majority of functional parameters of the mitochondria (p>0.05).

Calcium signaling-mediated endogenous protection of cell energetics in the acutely diabetic myocardium.

In acute diabetic myocardium, calcium signals propagated by intracellular calcium transients participate in the protection of cell energetics via upregulating the formation of mitochondrial energy transition pores (ETP). Mechanisms coupling ETP formation with an increase in membrane fluidity and a decrease in transmembrane potential of the mitochondria are discussed. Our results indicate that the amplification of calcium transients in the diabetic heart is associated with an increase in their amplitude.

Induction of carbonic anhydrase IX by hypoxia and chemical disruption of oxygen sensing in rat fibroblasts and cardiomyocytes.

CA IX is an active transmembrane carbonic anhydrase isoform functionally implicated in cell adhesion and pH control. Human CA IX is strongly induced by hypoxia and frequently associated with various tumors. In this study, we investigated the expression of the rat CA IX in response to chronic hypoxia and to treatment with chemical compounds that disrupt oxygen sensing, including dimethyloxalylglycine, dimethylester succinate, diazoxide, and tempol.

Mitochondrial membrane fluidity, potential, and calcium transients in the myocardium from acute diabetic rats.

In this study, we report for the first time concurrent measurements of membrane potential and dynamics and respiratory chain activities in rat heart mitochondria, as well as calcium transients in the hearts of rats in an early phase of streptozotocin diabetes, not yet accompanied with diabetes-induced complications. Quantitative relationships among these variables were assessed. The mitochondria from diabetic rats exhibited decreased fluorescence anisotropy values of diphenylhexatriene.

Bongkrekic acid and atractyloside inhibits chloride channels from mitochondrial membranes of rat heart.

The aim of this work was to characterize the effect of bongkrekic acid (BKA), atractyloside (ATR) and carboxyatractyloside (CAT) on single channel properties of chloride channels from mitochondria. Mitochondrial membranes isolated from a rat heart muscle were incorporated into a bilayer lipid membrane (BLM) and single chloride channel currents were measured in 250/50 mM KCl cis/trans solutions. BKA (1-100 microM), ATR and CAT (5-100 microM) inhibited the chloride channels in dose-dependent manner.

Remodelling of the sarcolemma in diabetic rat hearts: the role of membrane fluidity.

The hyperglycaemia and oxidative stress, that occur in diabetes mellitus, cause impairment of membrane functions in cardiomyocytes. Also reduced sensitivity to Ca-overload was reported in diabetic hearts (D). This enhanced calcium resistance is based on remodelling of the sarcolemmal membranes (SL) with down-regulated, but from the point of view of kinetics relatively well preserved Na,K-ATPase and abnormal Mg- and Ca-ATPase (Mg/Ca-ATPase) activities.

Regulation of mitochondrial contact sites in neonatal, juvenile and diabetic hearts.

Mitochondrial contact sites (MiCS) are dynamic structures involved in high capacity transport of energy from mitochondria into the cytosole. Previous studies revealed that in normal conditions the actual number of MiCS is in correlation with the energy requirements of the heart, particularly with those for its contractile work. Although the detailed mechanisms of signalling between the processes of energy utilisation and MiCS formation in the heart are not yet elucidated, it is known that intracellular Ca2+ transients are intimately involved in this crosstalk.