Muscle contraction increases carnitine uptake via translocation of OCTN2

Journal Article · Fri Feb 24 04:00:00 EST 2012 · Biochemical and Biophysical Research Communications

DOI:https://doi.org/10.1016/J.BBRC.2012.01.101· OSTI ID:22207724

Furuichi, Yasuro ^[1]; Sugiura, Tomoko; Kato, Yukio ^[2]; Takakura, Hisashi ^[3]; Hanai, Yoshiteru ^[4]; Hashimoto, Takeshi ^[5]; Masuda, Kazumi ^[3]

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1. Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa (Japan)
2. Faculty of Pharmacy, Kanazawa University, Kanazawa (Japan)
3. Faculty of Human Sciences, Kanazawa University, Kanazawa (Japan)
4. Nagoya Institute of Technology, Nagoya (Japan)
5. Ritsumeikan University, Kusatsu (Japan)

Highlights: Black-Right-Pointing-Pointer Muscle contraction augmented carnitine uptake into rat hindlimb muscles. Black-Right-Pointing-Pointer An increase in carnitine uptake was due to an intrinsic clearance, not blood flow. Black-Right-Pointing-Pointer Histochemical analysis showed sarcolemmal OCTN2 was emphasized after contraction. Black-Right-Pointing-Pointer OCTN2 protein in sarcolemmal fraction was increased in contracting muscles. -- Abstract: Since carnitine plays an important role in fat oxidation, influx of carnitine could be crucial for muscle metabolism. OCTN2 (SLC22A5), a sodium-dependent solute carrier, is assumed to transport carnitine into skeletal muscle cells. Acute regulation of OCTN2 activity in rat hindlimb muscles was investigated in response to electrically induced contractile activity. The tissue uptake clearance (CL{sub uptake}) of L-[{sup 3}H]carnitine during muscle contraction was examined in vivo using integration plot analysis. The CL{sub uptake} of [{sup 14}C]iodoantipyrine (IAP) was also determined as an index of tissue blood flow. To test the hypothesis that increased carnitine uptake involves the translocation of OCTN2, contraction-induced alteration in the subcellular localization of OCTN2 was examined. The CL{sub uptake} of L-[{sup 3}H]carnitine in the contracting muscles increased 1.4-1.7-fold as compared to that in the contralateral resting muscles (p < 0.05). The CL{sub uptake} of [{sup 14}C]IAP was much higher than that of L-[{sup 3}H]carnitine, but no association between the increase in carnitine uptake and blood flow was obtained. Co-immunostaining of OCTN2 and dystrophin (a muscle plasma membrane marker) showed an increase in OCTN2 signal in the plasma membrane after muscle contraction. Western blotting showed that the level of sarcolemmal OCTN2 was greater in contracting muscles than in resting muscles (p < 0.05). The present study showed that muscle contraction facilitated carnitine uptake in skeletal muscles, possibly via the contraction-induced translocation of its specific transporter OCTN2 to the plasma membrane.

• OSTI ID: 22207724
• Journal Information: Biochemical and Biophysical Research Communications, Journal Name: Biochemical and Biophysical Research Communications Journal Issue: 4 Vol. 418; ISSN 0006-291X; ISSN BBRCA9
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
BLOOD FLOW
CARBON 14
CARNITINE
CLEARANCE
CONTRACTION
IN VIVO
METABOLISM
MUSCLES
OXIDATION
PHOSPHATES
PROTEINS
RADIONUCLIDE KINETICS
RATS
TRANSLOCATION
TRITIUM
UPTAKE