| Autor: |
Abbott, Marcia J., Bogachus, Lindsey D., Turcotte, Lorraine P. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physiology; Jul2011, Vol. 111 Issue 1, p125-134, 10p |
| Abstrakt: |
AMP-activated protein kinase (AMPK) is a fuel sensor in skeletal muscle with multiple downstream signaling targets that may be triggered by increases in intracellular Ca2+ concentration ([Ca2+]). The purpose of this study was to determine whether increases in intracellular [Ca2+] induced by caffeine act solely via AMPKa2 and whether AMPKα2 is essential to increase glucose uptake, fatty acid (FA) uptake, and FA oxidation in contracting skeletal muscle. Hindlimbs from wild-type (WT) or AMPK α2 dominant-negative (DN) transgene mice were perfused during rest (n = 11), treatment with 3 mM caffeine (n = 10), or muscle contraction (n = 11). Time-dependent effects on glucose and FA uptake were uncovered throughout the 20-min muscle contraction perfusion period (P < 0.05). Glucose uptake rates did not increase in DN mice during muscle contraction until the last 5 min of the protocol (P < 0.05). FA uptake rates were elevated at the onset of muscle contraction and diminished by the end of the protocol in DN mice (P < 0.05). FA oxidation rates were abolished in the DN mice during muscle contraction (P < 0.05). The DN transgene had no effect on caffeine-induced FA uptake and oxidation (P > 0.05). Glucose uptake rates were blunted in caffeine-treated DN mice (P < 0.05). The DN transgene resulted in a greater use of intramuscular triglycerides as a fuel source during muscle contraction. The DN transgene did not alter caffeine- or contraction-mediated changes in the phosphorylation of Ca2+/calmodulin-dependent protein kinase I or ERK1/2 (P > 0.05). These data suggest that AMPKα2 is involved in the regulation of substrate uptake in a time-dependent manner in contracting muscle but is not necessary for regulation of FA uptake and oxidation during caffeine treatment. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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