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- Tähepõld, P, et al.
(författare)
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Exposure of rats to hyperoxia enhances relaxation of isolated aortic rings and reduces infarct size of isolated hearts.
- 2002
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 175:4, s. 271-7
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Tidskriftsartikel (refereegranskat)abstract
- Exposure of rats to hyperoxia before organ harvesting protected their isolated hearts against global ischaemia-reperfusion injury in a previous study. The present study investigates whether hyperoxia influences vasomotor function and regional ischaemia of the heart. Isolated rings of the thoracic aorta were obtained from rats immediately or 24 h after in vivo exposure to 60 min of hyperoxia (>95% O2), and the in vitro dose-response to phenylephrine (PHE), prostaglandin F2alpha (PGF2alpha) and endothelin-1 (ET-1), acetylcholine (Ach) and sodium nitroprusside (SNP) was assessed. Hyperoxia in vivo increased the relaxation of aortic rings to Ach and SNP, while it delayed contraction to PHE. The effect was more evident when the vessels were harvested immediately rather than 24 h after hyperoxic exposure. In separate experiments rat hearts were isolated immediately after hyperoxia, buffer-perfused, and subjected to 30 min of regional ischaemia and reperfused for 120 min. Infarct size was determined by triphenyl tetrazolium chloride staining. Hyperoxia significantly reduced infarct size. In normoxic controls 23.0 +/- 8.3% of the area at risk was infarcted, while in hyperoxic animals infarct size was 14.8 +/- 5.6% of the area at risk (P = 0.012). Exposure of rats to hyperoxia modifies the vasomotor response of isolated aortic rings, and reduces the infarct size of isolated rat heart. These novel aspects of hyperoxic treatment require further studies to explore the potential of its clinical application.
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- Olsen, Thomas, et al.
(författare)
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Exhaustive Exercise and Post-exercise Protein Plus Carbohydrate Supplementation Affect Plasma and Urine Concentrations of Sulfur Amino Acids, the Ratio of Methionine to Homocysteine and Glutathione in Elite Male Cyclists
- 2020
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Plasma and tissue sulfur amino acid (SAA) availability are crucial for intracellular methylation reactions and cellular antioxidant defense, which are important processes during exercise and in recovery. In this randomized, controlled crossover trial among eight elite male cyclists, we explored the effect of exhaustive exercise and post-exercise supplementation with carbohydrates and protein (CHO+PROT) vs. carbohydrates (CHO) on plasma and urine SAAs, a potential new marker of methylation capacity (methionine/total homocysteine ratio [Met/tHcy]) and related metabolites. The purpose of the study was to further explore the role of SAAs in exercise and recovery. Athletes cycled to exhaustion and consumed supplements immediately after and in 30 min intervals for 120 min post-exercise. After ~18 h recovery, performance was tested in a time trial in which the CHO+PROT group cycled 8.5% faster compared to the CHO group (41:53 ± 1:51 vs. 45:26 ± 1:32 min, p < 0.05). Plasma methionine decreased by ~23% during exhaustive exercise. Two h post-exercise, further decline in methionine had occured by ~55% in the CHO group vs. ~33% in the CHO+PROT group (pgroup × time < 0.001). The Met/tHcy ratio decreased by ~33% during exhaustive exercise, and by ~54% in the CHO group vs. ~27% in the CHO+PROT group (pgroup × time < 0.001) post-exercise. Plasma cystathionine increased by ~72% in the CHO group and ~282% in the CHO+PROT group post-exercise (pgroup × time < 0.001). Plasma total cysteine, taurine and total glutathione increased by 12% (p = 0.03), 85% (p < 0.001) and 17% (p = 0.02), respectively during exhaustive exercise. Using publicly available transcriptomic data, we report upregulated transcript levels of skeletal muscle SLC7A5 (log2 fold-change: 0.45, FDR:1.8e-07) and MAT2A (log2 fold-change: 0.38, FDR: 3.4e-0.7) after acute exercise. Our results show that exercise acutely lowers plasma methionine and the Met/tHcy ratio. This response was attenuated in the CHO+PROT compared to the CHO group in the early recovery phase potentially affecting methylation capacity and contributing to improved recovery.
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