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Increased VO2 max with right-shifted Hb-O2 dissociation curve at a constant O2 delivery in dog muscle in situ 总被引:1,自引:0,他引:1
Richardson Russell S.; Tagore Kuldeep; Haseler Luke J.; Jordan Maria; Wagner Peter D. 《Journal of applied physiology》1998,84(3):995-1002
If the diffusive component ofO2 transport in muscle isimportant in determining exercise capacity, an increasedcapillary-to-tissue PO2 differenceshould enhance gas exchange from blood to skeletal muscle duringexercise. Thus a rightward shift in theO2 dissociation curve shouldtheoretically increase O2extraction and improve maximal O2uptake (O2 max). Totest this hypothesis, we used the canine gastrocnemius muscle to studymaximal exercise in eight dogs at a normalP50 (33.1 ± 0.4 Torr) and withthe O2 dissociation curve shifted to the right by anallosteric modifier of hemoglobin (Hb) (methylpropionic acid, RSR-13;P50 = 53.2 ± 5.0 Torr). Fourcontrol dogs were also studied before and after infusion of vehicle.O2 (100%) was inspired duringexercise to maintain arterial saturation in both conditions. The musclewas surgically isolated and electrically stimulated (tetanic train: 0.2-ms stimuli for 200-ms duration at 50 Hz, once per s). Tomaintain O2 delivery (pre-RSR-13 = 19.1 ± 2.9; RSR-13 = 19.6 ± 2.5 ml · 100 g1 · min1),the muscle was pump perfused. At a constantO2 delivery, RSR-13 significantlyincreased percent O2 extraction(pre-RSR-13 = 61 ± 4.0; RSR-13 = 75.5 ± 4.7) andmuscle O2 max(pre-RSR-13 = 11.8 ± 2.1; RSR-13 = 14.2 ± 1.5 ml · 100 g1 · min1).This improvement inO2 max with increasedP50 demonstrates itsO2 supply dependence whenP50 is normal and the importance of O2 diffusive transport tomuscle at maximal exercise. 相似文献
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Kayser B.; Ferretti G.; Grassi B.; Binzoni T.; Cerretelli P. 《Journal of applied physiology》1993,75(3):1070-1074
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Jian-Ying Zhao Feng-Qi Zhao Hong-Xu Gao Xue-Hai Ju 《Journal of molecular modeling》2013,19(4):1789-1799
A theoretical study of the chemisorption and dissociation pathways of water on the Al13 cluster was performed using the hybrid density functional B3LYP method with the 6-311+G(d, p) basis set. The activation energies, reaction enthalpies, and Gibbs free energy of activation for the reaction were determined. Calculations revealed that the H2O molecule is easily adsorbed onto the Al13 surface, forming adlayers. The dissociation of the first H2O molecule from the bimolecular H2O structure via the Grotthuss mechanism is the most kinetically favorable among the five potential pathways for O–H bond breaking. The elimination of H2 in the reaction of an H2O molecule with a hydrogen atom on the Al cluster via the Eley–Rideal mechanism has a lower activation barrier than the elimination of H2 in the reaction of two adsorbed H atoms or the reaction of OH and H. Following the adsorption and dissociation of H2O, the structure of Al13 is distorted to varying degrees. Figure
Potential energy surface along the reaction coordinate for steps 5–9, calculated at the B3LYP/6-311+G(d,p) level 相似文献
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