Skeletal muscle contraction rapidly increases the translocation of glucose transporters (GLUTs) to facilitate the transport of glucose across the cell membrane. The prevailing concept holds that sarcoplasmatic reticulum (SR) Ca2+ release is neccesary and sufficient to cause a substantial feed-forward increase in glucose transport, with subsequent fine-tuning by feed-back signals relating to the muscle work-load. In the work presented here, a series of experiments were performed in incubated mouse muscles to scrutinize this model. Our data challenge the current Ca2+-centric paradigm by showing that increased cytosolic Ca2+ coming from the SR was unable to stimulate glucose transport in the absence of signals relating to ATP turnover and mechanical stress. Conversely, artificial activation of AMPK and mechanical stress-signaling elicited a full contraction-mimicking glucose transport-response without increasing Ca2+ signaling. These results call for a major reconsideration of the current working model describing glucose uptake in contracting skeletal muscle and may provide a useful framework for future investigations.
Physiology 2014 (London, UK) (2014) Proc Physiol Soc 31, SA079
Research Symposium: Does Ca2+ increase glucose uptake in skeletal muscle?
T. E. Jensen1, L. Sylow1, A. J. Rose2, S. J. Maarbjerg1, E. A. Richter1
1. Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark. 2. German Cancer Research Center (DKFZ), University of Heidelberg, Heidelberg, Germany.
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