Isoform-specific regulation of the lactate transporters MCT1 and MCT4 by contractile activity.
We examined the isoform-specific regulation of monocarboxylate transporter (MCT)1 and MCT4 expression by contractile activity in red and white tibialis anterior muscles. After 1 and 3 wk of chronic muscle stimulation (24 h/day), MCT1 protein expression was increased in the red muscles (+78%, P < 0.05). In the white muscles, MCT1 was increased after 1 wk (+191%) and then was decreased after 3 wk. In the red muscle, MCT1 mRNA accumulation was increased only after 3 wk (+21%; P < 0.05). In the white muscle, MCT1 mRNA was increased after 1 wk (+30%; P < 0.05) and 3 wk (+15%; P < 0.05). MCT4 protein was not altered in either the red or white muscles after 1 or 3 wk. MCT4 mRNA was transiently lowered (approximately 15%) in both muscles in the 1st wk, but MCT4 mRNA levels were back to control levels after 3 wk. In conclusion, chronic contractile activity induces the expression of MCT1 but not MCT4. This increase in MCT1 alone was sufficient to increase lactate uptake from the circulation.
Bonen
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A
Department of Kinesiology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. abonen@healthy.uwaterloo.ca
Tonouchi
M
M
Miskovic
D
D
Heddle
C
C
Heikkila
J J
JJ
Halestrap
A P
AP
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D004558:Electric Stimulation; D005786:Gene Expression Regulation; D006019:Glycolysis; D008297:Male; D027501:Monocarboxylic Acid Transporters; D009119:Muscle Contraction / Q000502:physiology*; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism; D009124:Muscle Proteins; D010084:Oxidation-Reduction; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D002352:Carrier Proteins; D027501:Monocarboxylic Acid Transporters; D009124:Muscle Proteins; D012333:RNA, Messenger; C516342:Slc16a3 protein, rat