Geor R J, Larsen L, Waterfall H L, Stewart-Hunt L, McCutcheon L J
Department of Biomedical Science, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada.
Equine Vet J Suppl. 2006 Aug(36):590-5. doi: 10.1111/j.2042-3306.2006.tb05610.x.
No studies in horses have examined the effect of route of carbohydrate (glucose) administration on the rate of muscle glycogen storage following glycogen-depleting exercise.
Glucose delivery from the gastrointestinal tract limits the rate of muscle glycogen storage following glycogen-depleting exercise.
In a crossover design, 7 fit horses completed treadmill exercise (EX) on 3 occasions to deplete muscle glycogen by approximately 50%. After EX horses received: 1) i.v. glucose infusion (IV; 0.5 g/kg bwt/h for 6 h), 2) oral glucose boluses (OR; 1 g/kg bwt at 0, 2 and 4 h post EX) or 3) no glucose supplementation (CON). Blood samples for measurement of glucose and insulin concentrations were collected before EX and during the 6 h treatment period. Muscle biopsies for measurement of muscle glycogen content (GLY) and glycogen synthase (GS) activity were taken before and after exercise and at 3 and 6 h.
Mean plasma glucose concentrations were significantly higher in IV and OR than in CON throughout treatment. The average serum insulin responses in IV and OR treatments were also significantly greater than in CON. After EX, GLY was not different among the 3 treatments. However, glycogen storage rates were significantly higher in IV than in CON and OR during the first 3 h and second 3 h of recovery, and GLY was significantly higher in IV than in OR and CON at 6 h of recovery. GS activity was significantly higher in IV than in OR and CON at 3 h of recovery.
Muscle glycogen storage in horses during a 6 h period after exercise was enhanced by i.v. glucose administration (3 g/kg) but not by an equivalent glucose dose administered per os. While oral administration of glucose achieved a level of hyperglycaemia and hyperinsulinaemia that markedly accelerates glycogen storage in other species, the rate of glycogen storage following oral supplementation was not different to control conditions.
Glucose supplementation via the i.v. route should be considered when rapid replenishment of muscle glycogen stores is desired.
尚无针对马匹的研究探讨碳水化合物（葡萄糖）给药途径对糖原耗竭运动后肌肉糖原储存速率的影响。
胃肠道的葡萄糖输送限制了糖原耗竭运动后肌肉糖原的储存速率。
采用交叉设计，7匹健康马匹分3次完成跑步机运动（EX），以使肌肉糖原消耗约50%。运动后，马匹接受：1）静脉输注葡萄糖（IV；0.5 g/kg体重/小时，持续6小时），2）口服葡萄糖推注（OR；运动后0、2和4小时，1 g/kg体重），或3）不补充葡萄糖（CON）。在运动前和6小时治疗期内采集血样以测定葡萄糖和胰岛素浓度。在运动前后以及运动后3小时和6小时进行肌肉活检，以测定肌肉糖原含量（GLY）和糖原合酶（GS）活性。
在整个治疗过程中，IV组和OR组的平均血浆葡萄糖浓度显著高于CON组。IV组和OR组治疗后的平均血清胰岛素反应也显著高于CON组。运动后，3种治疗方法之间的GLY没有差异。然而在恢复的前3小时和第二个3小时，IV组的糖原储存率显著高于CON组和OR组，在恢复6小时时，IV组的GLY显著高于OR组和CON组。在恢复3小时时IV组的GS活性显著高于OR组和CON组。
运动后6小时内，静脉注射葡萄糖（3 g/kg）可增强马匹肌肉糖原的储存，但口服等量葡萄糖则无此效果。虽然口服葡萄糖可达到高血糖和高胰岛素血症水平，从而显著加速其他物种糖原的储存，但口服补充后的糖原储存速率与对照条件并无差异。
当需要快速补充肌肉糖原储备时，应考虑通过静脉途径补充葡萄糖。
