Gladden L B, Crawford R E, Webster M J, Watt P W
Department of Health and Human Performance, Auburn University, Alabama 36849.
J Appl Physiol (1985). 1995 Jan;78(1):205-11. doi: 10.1152/jappl.1995.78.1.205.
This study evaluated the effects of various lactate transport inhibitors and competitors on rapid tracer lactate influx into the canine gastrocnemius-plantaris muscle (GP). GPs of 25 anesthetized dogs were perfused with red blood cell-free media in situ. At 0.9 mM lactate concentration ([La]), GP oxygen uptake (2.6 +/- 0.1 ml.kg-1.min-1) and net lactate output (-0.039 +/- 0.007 mmol.kg-1.min-1) were similar to values during blood perfusion. Rapid tracer lactate influx was inferred by a paired-tracer dilution method at nominal perfusate [La] values of 1, 5, 10, 25, and 50 mM. The maximal tracer influx rate (Umax) decreased significantly with each increase in unlabeled [La]. A saturation effect was suggested by the fact that percent inhibition of Umax began to reach a plateau at the higher unlabeled [La] values. The inhibition of Umax was 20.5 +/- 2.9% at 5 mM, 34.1 +/- 3.3% at 10 mM, 47.3 +/- 2.7% at 25 mM, and 56.1 +/- 2.8% at 50 mM [La]. Umax was also inhibited by various inhibitors/competitors of lactate transport as follows (% inhibition): 50 mM alpha-cyano-4-hydroxy-cinnamate (69.2 +/- 4.9%), 1.5 mM phloretin (25.4 +/- 5.5%), 0.1 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (0.3 +/- 1.9%), 0.5 mM p-chloromercuribenzenesulfonic acid (72.9%), 0.5 mM furosemide (+ 2.8%), 25 mM pyruvate (52.4 +/- 2.9%), and 50 mM DL-lactate (50.2 +/- 4.0%). These experiments support the notion that lactate influx into canine skeletal muscle is a function of both a linear (possible diffusive) component and a Michaelis-Menten (carrier-mediated) component.
本研究评估了各种乳酸转运抑制剂和竞争剂对示踪剂乳酸快速流入犬腓肠肌-比目鱼肌（GP）的影响。对25只麻醉犬的GP在体灌注无红细胞培养基。在乳酸浓度（[La]）为0.9 mM时，GP的氧摄取量（2.6±0.1 ml·kg-1·min-1）和净乳酸输出量（-0.039±0.007 mmol·kg-1·min-1）与血液灌注时的值相似。通过配对示踪剂稀释法在名义灌注液[La]值为1、5、10、25和50 mM时推断示踪剂乳酸的快速流入。随着未标记[La]的每次增加，最大示踪剂流入速率（Umax）显著降低。在较高的未标记[La]值时，Umax抑制百分比开始达到平台期，这表明存在饱和效应。在[La]为5 mM时，Umax的抑制率为20.5±2.9%，10 mM时为34.1±3.3%，25 mM时为47.3±2.7%，50 mM时为56.1±2.8%。Umax也受到以下各种乳酸转运抑制剂/竞争剂的抑制（抑制百分比）：50 mMα-氰基-4-羟基肉桂酸（69.2±4.9%）、1.5 mM根皮素（25.4±5.5%）、0.1 mM 4,4'-二异硫氰基芪-2,2'-二磺酸（0.3±1.9%）、0.5 mM对氯汞苯磺酸盐（72.9%）、0.5 mM呋塞米（+2.8%）、25 mM丙酮酸（52.4±2.9%）和50 mM DL-乳酸（50.2±4.0%）。这些实验支持了乳酸流入犬骨骼肌是线性（可能是扩散性的）成分和米氏（载体介导的）成分共同作用的观点。
