Gladden L B, Crawford R E, Webster M J
Department of Health and Human Performance, Auburn University, Alabama 36849-5323.
J Appl Physiol (1985). 1992 May;72(5):1826-30. doi: 10.1152/jappl.1992.72.5.1826.
The purpose of this study was to determine the effect of blood flow on net lactate uptake (L) at constant elevated blood lactate concentration and metabolic rate in the in situ dog gastrocnemius-plantaris (GP) muscle. In all experiments, an infusion of lactate/lactic acid at a pH of 3.8 established a blood lactate concentration of 10-13 mM while maintaining normal blood gas/pH status as the GP was stimulated to contract with twitches at 1 Hz. In series 1 (n = 14), blood flow (ml.kg-1.min-1) was controlled by a pump at either 1) the spontaneous level for 1-Hz contractions (control flow = 332 +/- 23) or 2) a level estimated to be approximately 65% greater (high flow = 543 +/- 42). In series 2 (n = 7), perfusion pressure was varied during 1-Hz contractions. Four different perfusion pressures (80, 120, 155, and 180 Torr) were presented to each GP preparation, resulting in mean flow rates of 308 +/- 34, 419 +/- 30, 492 +/- 37, and 646 +/- 30 ml.kg-1.min-1. Increasing blood flow had no significant effect on net L in series 1. Similarly, there was no significant change in net L across the first three perfusion pressures/flow rates in series 2. However, net L (mmol.kg-1.min-1) was significantly increased in the highest perfusion pressure/flow rate period (from 0.335 +/- 0.029 at 80 Torr to 0.431 +/- 0.034 at 180 Torr). This study suggests that blood flow may have an independent effect on net L at the upper extreme of the normal blood flow range during contractions but very little effect over a fairly wide low-to-middle range of flow rates.
本研究的目的是在原位犬腓肠肌 - 比目鱼肌（GP）肌肉中，在恒定升高的血乳酸浓度和代谢率条件下，确定血流对净乳酸摄取（L）的影响。在所有实验中，以pH 3.8输注乳酸/乳酸溶液，使血乳酸浓度达到10 - 13 mM，同时在以1 Hz的频率刺激GP收缩时维持正常的血气/pH状态。在第1组实验（n = 14）中，血流（ml·kg⁻¹·min⁻¹）由泵控制，分别为：1）1 Hz收缩时的自发水平（对照血流 = 332 ± 23）或2）估计比自发水平高约65%的水平（高血流 = 543 ± 42）。在第2组实验（n = 7）中，在1 Hz收缩期间改变灌注压力。向每个GP标本施加四种不同的灌注压力（80、120、155和180 Torr），导致平均流速分别为308 ± 34、419 ± 30、492 ± 37和646 ± 30 ml·kg⁻¹·min⁻¹。在第1组实验中，增加血流对净L没有显著影响。同样，在第2组实验的前三个灌注压力/流速条件下，净L也没有显著变化。然而，在最高灌注压力/流速阶段，净L（mmol·kg⁻¹·min⁻¹）显著增加（从80 Torr时的0.335 ± 0.029增加到180 Torr时的0.431 ± 0.034）。本研究表明，在收缩期间，血流在正常血流范围的上限可能对净L有独立影响，但在相当宽的低至中等流速范围内影响很小。
