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Effects of high-intensity training on MCT1, MCT4, and NBC expressions in rat skeletal muscles: influence of chronic metabolic alkalosis

¹Université Montpellier 1, UFR Médecine EA701, F-34295, Montpellier; ²Institut National de la Santé et de la Recherche, ERI 25, F-34295, Montpellier; ³Université Evry Val d'Essonne, UFR Sciences fondamentales et appliquées, EA3872, Département Sciences et Techniques des Activités Physiques et Sportives, F-91025, Evry, France; and ⁴Facoltà di Scienze Motorie, Università degli Studi di Verona, Verona, Italy

Submitted 13 March 2007 ; accepted in final form 28 June 2007

This study investigated the effects of high-intensity training, with or without induced metabolic alkalosis, on lactate transporter (MCT1 and MCT4) and sodium bicarbonate cotransporter (NBC) content in rat skeletal muscles. Male Wistar rats performed high-intensity training on a treadmill 5 times/wk for 5 wk, receiving either sodium bicarbonate (ALK-T) or a placebo (PLA-T) prior to each training session, and were compared with a group of control rats (CON). MCT1, MCT4, and NBC content was measured by Western blotting in soleus and extensor digitorum longus (EDL) skeletal muscles. Citrate synthase (CS) and phosphofructokinase (PFK) activities and muscle buffer capacity (m) were also evaluated. Following training, CS and PFK activities were significantly higher in the soleus only (P < 0.05), whereas m was significantly higher in both soleus and EDL (P < 0.05). MCT1 (PLA-T: 30%; ALK-T: 23%) and NBC contents (PLA-T: 85%; ALK-T: 60%) increased significantly only in the soleus following training (P < 0.01). MCT4 content in the soleus was significantly greater in ALK-T (115%) but not PLA-T compared with CON. There was no significant change in protein content in the EDL. Finally, NBC content was related only to MCT1 content in soleus (r = 0.50, P < 0.01). In conclusion, these results suggest that MCT1, MCT4, and NBC undergo fiber-specific adaptive changes in response to high-intensity training and that induced alkalosis has a positive effect on training-induced changes in MCT4 content. The correlation between MCT1 and NBC expression suggests that lactate transport may be facilitated by NBC in oxidative skeletal muscle, which may in turn favor better muscle pH regulation.

monocarboxylate transporter; sodium bicarbonate transporter; lactate transporter; muscle pH regulation; exercise

This article has been cited by other articles:

				D. Bishop, J. Edge, C. Thomas, and J. Mercier Effects of high-intensity training on muscle lactate transporters and postexercise recovery of muscle lactate and hydrogen ions in women Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2008; 295(6): R1991 - R1998. [Abstract] [Full Text] [PDF]