Lactate/H + uptake by red blood cells during exercise alters their physical properties

Abstract

We investigated whether uptake of lactate anions by red blood cells (RBC) during maximal exercise altered certain cellular physical properties including volume, density and osmotic fragility. Irrespective of whether individuals undertook 1 min of exercise at maximal effort or a progressive exercise test to exhaustion, whole-blood lactate concentration increased about tenfold relative to pre-exercise values (P < 0.001). The plasma and cellular concentrations of lactate increased uniformly, which maintained a constant plasma-to-cell gradient. Exercise-induced increases in RBC osmotic fragility (P < 0.001) and mean cell volume (MCV; P < 0.05), and decreases in mean cell haemoglobin concentration (MCHC; P < 0.05) and cell density (P < 0.005) also occurred. These exercise-induced cellular responses could be simulated in vitro by treating blood with L-lactic acid (15 mM), but not by low pH (7.1) or L-lactate alone. The uptake of lactate by RBCs during vigorous exercise alters certain cellular properties. Although the physiological implications of these changes are unclear, the traditional view that the lactate anion has no known harmful effects should be reconsidered.

Does exercise-induced hypoxemia modify lactate influx into erythrocytes and hemorheological parameters in athletes?

“…Usually, RBC deformability decreases with exercise (5,29). The increased plasma [Lac] and decreased pH that occur during exercise lead to water loss by RBCs (osmotic process), which, in turn, results in greater rigidity (20,32). In our study, however, the rise in plasma [Lac] during exercise was slight in all subjects, which can explain the lack of RBC rigidity change.…”

“…One can thus think that repeated mild hypoxemia stimulus may lead to increased expression or activity of band 3 and MCT-1 proteins on the red blood cell (RBC) membranes. An increase in lactate and H ϩ fluxes into RBCs during exercise may also alter the deformability of these cells, because lactate uptake by RBCs increases their rigidity (32). These changes in RBC deformability could, in turn, alter blood rheological properties and then participate to EIH.…”

<b>Cellular distributions of monocarboxylate transporters: a r</b><b>eview </b>

“…The plasma membrane of hematopoietic cells, mainly erythrocytic progenitor cells, is selectively immunolabeled for MCT1 in the murine bone marrow (144). Sustained exercise releases a great amount of lactate into the blood to induce a lactate influx from the plasma to erythrocytes (133). Training is known to elevate MCT1 concentration of skeletal muscle and heart depending on the intensity of training (3,113).…”

Faster lactate transport across red blood cell membrane in sickle cell trait carriers

“…As suggested by Smith et al (30), a greater lactate influx into the RBCs of AS than of AA could be involved in the reported cases of sudden death in SCT carriers after strenuous exercise (8). Excessive uptake of lactate by AS RBCs could trigger the sickling process because of the subsequent dehydration caused by activation of the volume-and pH-dependent K ϩ /Cl Ϫ cotransport channels (30). This may lead, in turn, to hypoxia through microvascular obstruction and, sometimes, to fatal medical complications (8,30).…”

“…Moreover, faster lactate influx into AS RBCs than into AA RBCs has been suggested (30) to explain the occurrence of sudden death under strenuous conditions in some SCT individuals (8), but this has never been specifically demonstrated. The aim of the present study was thus to investigate RBC lactate transport activity in AS and AA subjects having the same level of aerobic physical fitness.…”