Glutathione Upregulates the Expression of KATP Channels and Vasorelaxation Responses and Inhibits mPTP Opening and Oxidative Stress in the Heart Mitochondria of Old Rats.

Background: In the present work, we investigated the effect of exogenous glutathione in old rats on the expression of ATP-sensitive potassium (KATP) channels, the mitochondrial permeability transition pore (mPTP) opening in the heart, and the vasorelaxation responses of isolated aortic rings to activation of KATP channels. Methods: Experiments were performed on adult (6 months) and old (24 months) male Wistar rats, which were divided into three groups: adult, old, and glutathione-treated old rats. Glutathione was injected intraperitoneally at a dose of 52 mg/kg 1 hour before the studies. The mRNA expression of KATP channels was determined using reverse transcription and real-time polymerase chain reaction analysis. The effect of glutathione administration on mPTP opening, relaxation responses of isolated aortic rings, and oxidative stress markers was studied. Results: It was shown that the expression levels of Kir6.1, Kir6.2, and SUR1 subunits of KATP channels and levels of reduced glutathione were significantly increased in glutathione-treated old rats (by 8.3, 2.8, 13.1, and 1.5-fold, respectively), whereas the levels of oxidative stress markers (hydrogen peroxide, diene conjugates, malondialdehyde, and rate of superoxide generation) in heart mitochondria and mPTP opening were significantly reduced. Relaxation of aortic rings was significantly increased in response to the actions of KATP channel openers flocalin and pinacidil in glutathione-treated animals, which was prevented by glibenclamide. Conclusions: Thus, the administration of exogenous glutathione to old rats resulted in a significant increase in the expression levels of the Kir6.1, Kir6.2, and SUR1 subunits of KATP channels and a decrease in oxidative stress. This was accompanied by inhibition of mPTP opening and enhancement of vasorelaxation responses to activation of KATP channels.

Exercise restores endogenous H2 S synthesis and mitochondrial function in the heart of old rats.

BACKGROUND: Ageing is accompanied by a decrease in endogenous hydrogen sulphide (H2 S) synthesis and the development of mitochondrial dysfunction. The aim of our work was to study the possible participation of exercise training-induced regulation of endogenous H2 S production in the restoration of mitochondrial function in old rats. MATERIALS AND METHODS: Male rats were divided into three groups: adult, old and exercise-trained old. Exercise training of old rats was performed for 4 weeks. The mRNA expression cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST) were determined using reverse transcription and real-time polymerase chain reaction analysis. Mitochondrial dysfunction was determined by mPTP opening, which was investigated by spectrophotometric registration of the swelling of mitochondria isolated from the rat heart. We also studied the effect of exercise on H2 S content, oxidative stress and mtNOS activity. RESULTS: Exercise training in old animals significantly increased the expression of H2 S-synthesizing enzymes CSE and 3-MST and restored endogenous H2 S production in cardiac tissue and cardiac mitochondria to levels of adult animals. In addition, the training significantly reduced oxidative stress in old rats, in particular the rate of formation of •O2 - and H2 O2 , diene conjugates and malondialdehyde levels in the mitochondria of the heart. Simultaneously, in the hearts of these animals, resistance of mPTP to the inducer of its opening of calcium ions was increased. CONCLUSIONS: Thus, exercise training restores endogenous H2 S production, and significantly reduces oxidative stress in cardiac mitochondria of old rats that are associated with the inhibition of calcium-induced mPTP opening as an indicator of mitochondrial dysfunction.

Pyridoxal-5-phosphate induced cardioprotection in aging associated with up-expression of cystathionine-γ-lyase, 3-mercaptopyruvate sulfurtransferase, and ATP-sensitive potassium channels.

BACKGROUND: In the present work, we investigated the cardioprotective potential of pyridoxal-5-phosphate (PLP) in old rats as a cofactor of enzymes that synthesize hydrogen sulphide (H2 S). MATERIALS AND METHODS: PLP was administered per os in a dose of 0.7 mg per kg daily for 2 weeks. Rats were divided into three groups (adult, old and old +PLP) of 20 animals. The cardiac mRNA levels of genes encoding H2 S-synthesizing enzymes cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST), uncoupling proteins (UCP3), subunits of ATP-sensitive potassium (KATP ) channels were determined using real-time polymerase chain reaction analysis. We also studied the effect of PLP-administration on the content of H2 S, oxidative stress, the activities of inducible and constitutive NO-synthase (iNOS, cNOS), arginase and nitrate reductase in the heart homogenates as well as cardiac resistance to ischemia-reperfusion in Langendorff-isolated heart model. RESULTS: It was shown that PLP restored mRNA levels of CSE, 3-MST and UCP3 genes, and H2 S content and also significantly increased the expression of SUR2 and Kir6.1 (2.2 and 3.3 times, respectively) in the heart of old rats. PLP significantly reduced the formation of superoxide, malondialdehyde, diene conjugates as well as the activity of iNOS and arginase. PLP significantly increased constitutive synthesis of NO and prevented reperfusion disturbances of the heart function after ischemia. CONCLUSIONS: Thus, PLP-administration in old rats was associated with up-expression of CSE, 3-MST, UCP3 and SUR2 and Kir6.1 subunits of KATP channels, and also increased cNOS activity and reduced oxidative stress and prevented reperfusion dysfunction of the heart in ischemia-reperfusion.

Glutathione restores the mitochondrial redox status and improves the function of the cardiovascular system in old rats.

Introduction: Aging is accompanied by cardiovascular disorders which is associated with an imbalance of pro- and antioxidant systems, the mitochondrial dysfunction, etc. Glutathione (GSH) plays a critical role in protecting cells from oxidative damage. The aim of the work was to study the effect of exogenous glutathione on the redox status of mitochondria, the content of H2S and the function of the cardiovascular system in old rats. Methods: Experiments were performed on adult (6 months) and old (24 months) Wistar rats divided into three groups: adult, old and glutathionetreated old rats. Glutathione was injected intraperitoneally at a dose of 52 mg/kg. We investigated glutathione redox balance, H2S levels, oxidative stress, the opening of the mitochondrial permeability transition pore (mPTP), the resistance of isolated heart to ischemia/reperfusion in Langendorff model, endothelium-dependent vasorelaxation of isolated aortic rings, and cardiac levels of 3-MST, CSE, and UCP3 mRNA were determined using real-time PCR analysis. Results: Our data shows that in old rats treated with glutathione, the balance of its oxidized and reduced form changes in the direction of a significant increase (by 53.6%) of the reduced form. Glutathione pretreatment significantly increased the H2S levels, mtNOS activity, and UCP3 expression which considered as protective protein, and conversely, significantly decreased oxidative stress markers (the rate of O2•- generation, the levels of H2O2, diene conjugates and malone dialdehyde, in 2.5, 2.3, 2, and 1.6 times, respectively) in heart mitochondria. This was associated with the inhibition mitochondrial permeability transition pore opening and increased resistance of the isolated heart to ischemia/reperfusion in these animals. At the same time, in glutathione-treated old rats, we also observed restoration of endothelium-dependent vasorelaxation responses to acetylcholine, which were almost completely abolished by the NO-synthase inhibitor L-NAME. Conclusion: Thus, the pretreatment of old rats with glutathione restores the mitochondrial redox status and improves the function of the cardiovascular system.