Scheuermann B W, Kowalchuk J M, Paterson D H, Cunningham D A
School of Kinesiology, The University of Western Ontario, London, Ontario, Canada N6A 3K7.
J Appl Physiol (1985). 1998 Oct;85(4):1384-93. doi: 10.1152/jappl.1998.85.4.1384.
Inhibition of carbonic anhydrase (CA) is associated with a lower plasma lactate concentration ([La-]pl) during fatiguing exercise. We hypothesized that a lower [La-]pl may be associated with faster O2 uptake (V(O2)) kinetics during constant-load exercise. Seven men performed cycle ergometer exercise during control (Con) and acute CA inhibition with acetazolamide (Acz, 10 mg/kg body wt iv). On 6 separate days, each subject performed 6-min step transitions in work rate from 0 to 100 W (below ventilatory threshold, <VE(T)) or to a V(O2) corresponding to approximately 50% of the difference between the work rate at VE(T) and peak V(O2) (>VE(T). Gas exchange was measured breath by breath. Trials were interpolated at 1-s intervals and ensemble averaged to yield a single response. The mean response time (MRT, i.e., time to 63% of total exponential increase) for on- and off-transients was determined using a two- (<VE(T)) or a three-component exponential model (>VE(T)). Arterialized venous blood was sampled from a dorsal hand vein and analyzed for [La-]pl. MRT was similar during Con (31.2 +/- 2.6 and 32.7 +/- 1.2 s for on and off, respectively) and Acz (30.9 +/- 3.0 and 31.4 +/- 1.5 s for on and off, respectively) for work rates <VE(T). At work rates >VE(T), MRT was similar between Con (69.1 +/- 6.1 and 50.4 +/- 3.5 s for on and off, respectively) and Acz (69.7 +/- 5.9 and 53.8 +/- 3.8 s for on and off, respectively). On- and off-MRTs were slower for >VE(T) than for <VE(T) exercise. [La-]pl increased above 0-W cycling values during <VE(T) and >VE(T) exercise but was lower at the end of the transition during Acz (1.4 +/- 0.2 and 7.1 +/- 0.5 mmol/l for <VE(T) and >VE(T) respectively) than during Con (2.0 +/- 0.2 and 9.8 +/- 0.9 mmol/l for <VE(T) and >VE(T), respectively). CA inhibition does not affect O2 utilization at the onset of <VE(T) or >VE(T) exercise, suggesting that the contribution of oxidative phosphorylation to the energy demand is not affected by acute CA inhibition with Acz.
在疲劳运动期间，抑制碳酸酐酶（CA）与较低的血浆乳酸浓度（[La-]pl）相关。我们假设较低的[La-]pl可能与恒负荷运动期间更快的氧气摄取（V(O2)）动力学有关。七名男性在对照（Con）和用乙酰唑胺（Acz，10mg/kg体重静脉注射）进行急性CA抑制期间进行了自行车测力计运动。在6个不同的日子里，每个受试者进行6分钟的工作率从0到100W的阶跃转换（低于通气阈值，<VE(T)）或转换到对应于VE(T)时的工作率与峰值V(O2)之间差异的约50%的V(O2)（>VE(T)）。逐 breath 测量气体交换。试验以1秒间隔进行内插并进行总体平均以产生单个反应。使用二组分（<VE(T)）或三组分指数模型（>VE(T)）确定上升和下降瞬变的平均反应时间（MRT，即达到总指数增加的63%的时间）。从手背静脉采集动脉化静脉血并分析[La-]pl。对于<VE(T)的工作率，Con期间的MRT（上升和下降分别为31.2±2.6和32.7±1.2秒）和Acz期间的MRT（上升和下降分别为30.9±3.0和31.4±1.5秒）相似。在>VE(T)的工作率下，Con（上升和下降分别为69.1±%6.1和50.4±3.5秒）和Acz（上升和下降分别为69.7±5.9和53.8±3.8秒）之间的MRT相似。对于>VE(T)的运动，上升和下降MRT比<VE(T)的运动慢。在<VE(T)和>VE(T)运动期间，[La-]pl高于0-W骑行值，但在Acz期间转换结束时较低（<VE(T)和>VE(T)分别为1.4±0.2和7.1±0.5mmol/l），而在Con期间（<VE(T)和>VE(T)分别为2.0±0.2和9.8±0.9mmol/l）。CA抑制不会影响<VE(T)或>VE(T)运动开始时的氧气利用，这表明氧化磷酸化对能量需求的贡献不受Acz急性CA抑制的影响。
