A 2×2 factorial design was used to evaluate possible preservation
of mitochondrial functions in two cardioprotective experimental models, remote ischemic preconditioning and streptozotocin-induced diabetes mellitus, and their interaction during ischemia/reperfusion injury (I/R) of the heart. Male Wistar rats were randomly allocated into four groups: control (C), streptozotocin-induced diabetic (DM), preconditioned
(RPC) and preconditioned streptozotocin-induced diabetic (DM+RPC).
RPC was conducted by 3 cycles of 5-min hind-limb ischemia and 5-min reperfusion. DM was induced by a single dose of 65mg/kg streptozotocin. Isolated hearts were exposed to ischemia/reperfusion test according to Langendorff. Thereafter mitochondria were isolated and the mitochondrial respiration was measured. Additionally, the ATP synthase activity measurements on the same preparations were done. Animals of all groups subjected to I/Rexhibited a decreased state 3 respiration with the least change noted in DM+RPC group associated with no significant changes in state 2 respiration. In RPC, DM and DM+RPC group, no significant
changes in the activity of ATP synthase were observed after I/R
injury. These results suggest that the endogenous protective mechanisms of RPC and DM do preserve the mitochondrial function in heart when they act in combination.
Acute streptozotocin diabetes mellitus (DM) as well as remote ischemic preconditioning (RPC) has shown a favorable effect on the postischemic-reperfusion function of the myocardium. Cardioprotective mechanisms offered by these experimental models involve the mitochondria with the changes in functional properties of membrane as the end-effector. The aim was to find out whether separate effects of RPC and DM would stimulate the mechanisms of cardioprotection to a maximal level or whether RPC and DM conditions would cooperate in stimulation of cardioprotection. Experiments were performed on male Wistar rats divided into groups: control, DM, RPC and DM treated by RPC (RPC+DM). RPC protocol of 3 cycles of 5-min hind limb ischemia followed by 5-min reperfusion was used. Ischemicreperfusion injury was induced by 30-min ischemia followed by 40-min reperfusion of the hearts in Langendorff mode. Mitochondria were isolated by differential centrifugation, infarct size assessed by staining with 1 % 2,3,5-triphenyltetrazolium chloride, mitochondrial membrane fluidity with a fluorescent probe DPH, CoQ9 and CoQ10 with HPLC. Results revealed that RPC as well as DM decreased the infarct size and preserved mitochondrial function by increasing the mitochondrial membrane fluidity. Both used models separately offered a sufficient protection against ischemic-reperfusion injury without an additive effect of their combination., M. Ferko, I. Kancirová, M. Jašová, I. Waczulíková, S. Čarnická, J. Kucharská, O. Uličná, O. Vančová, M. Muráriková, T. Ravingerová, A. Ziegelhöffer., and Obsahuje bibliografii
Remote ischemic preconditioning (RIP)-induced protection of myocardial energetics was well documented on the level of tissue, but data concerning the involvement of mitochondria were missing. We aimed at the identification of changes in membrane properties and respiratory functions induced in rat heart mitochondria by RIP. Experiments were performed on 46 male Wistar rats divided into control and RIP-treated groups of 21 animals each. Blood flow in the occluded area was recorded by MRI angiography in four animals. RIP protocol comprised of three successive 5-min occlusions each followed by 5-min reperfusions of descending branches of the right hind limb femoral artery. The efficacy of RIP was evaluated as the extent of RIP-induced protection against damage to the functions of mitochondria isolated by differential centrifugation after 30-min global ischemia followed by 40-min reperfusion of the hearts in Langendorff mode. Assessments: mitochondrial membrane fluidity with a fluorescent probe DPH, CoQ9 and CoQ10 with HPLC, mitochondrial respiration with the Oxygraph-2k (Oroboros). Results revealed that RIP was affecting the mitochondria. The immediate protection conferred by RIP involves beneficial and prognostically significant effects: a total elimination of ischemia/reperfusion-induced depression of mitochondrial membrane fluidity and a trend for better preservation of mitochondrial state 3 respiration., M. Ferko, I. Kancirová, M. Jašová, S. Čarnická, M. Muráriková, I. Waczulíková, Z. Sumbalová, J. Kucharská, O. uličná, T. Ravingerová, A. Ziegelhöffer., and Obsahuje bibliografii
Pharmacological preconditioning by diazoxide and a model of experimental streptozotocin-induced acute diabetes mellitus (STZ-DM) provided similar levels of cardioprotection assessed as limiting myocardial infarct size. The aim was to explore the possibility of existence of another in vitro mechanism, which could be contributory to cardioprotection mediated by diazoxide treatment. Mitochondrial membrane fluidity and ATP synthase activity in isolated heart mitochondria were determined under the influence of two factors, STZ-DM condition and treatment with diazoxide. Both factors independently increased the ATP synthase activity (p<0.05), as no interaction effect was observed upon the combination of STZ-DM with diazoxide. On the other hand, the mitochondrial membrane fluidity was significantly increased by STZ-DM only; no significant main effect for diazoxide was found. Based on the results from measurements of enzyme kinetics, we assume a direct interaction of diazoxide with the molecule of ATP synthase stimulated its activity by noncompetitive activation. Our present work revealed, for the first time, that cardioprotection induced by diazoxide may not be caused exclusively by mitochondrial KATP opening, but presumably also by a direct interaction of diazoxide with ATP synthase, although the mechanisms for achieving this activation cannot be fully delineated., M. Jašová, I. Kancirová, M. Muráriková, V. Farkašová, I. Waczulíková, T. Ravingerová, A. Ziegelhöffer, M. Ferko., and Obsahuje bibliografii