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Ischaemia and insulin, but not ischaemia and contraction, act synergistically in stimulating muscle glucose uptake in vivo in humans.

Authors
  • Bosselaar, Marlies
  • Smits, Paul
  • Tack, Cees J
Type
Published Article
Journal
Clinical Science
Publisher
Portland Press
Publication Date
Jan 01, 2009
Volume
116
Issue
2
Pages
157–164
Identifiers
DOI: 10.1042/CS20080087
PMID: 18570630
Source
Medline
License
Unknown

Abstract

Ischaemia, like muscle contraction, has been reported to induce skeletal muscle glucose uptake in in vitro models. This stimulating effect appears independent of insulin and is probably mediated by activation of AMPK (AMP-activated protein kinase). In the present study, we hypothesized that in vivo in humans ischaemia- and insulin-induced glucose uptake are additive, and that the combined impact of ischaemia and contraction on glucose uptake is of a similar magnitude when each is applied separately. We assessed the effects of ischaemia with and without euglycaemic-hyperinsulinaemia (clamp; protocol 1) and with and without muscle contraction (protocol 2) on muscle FGU (forearm glucose uptake) in healthy subjects. Furthermore, we assessed the impact of ischaemia on FBF (forearm blood flow; plethysmography). In protocol 1, ischaemia increased FGU from 0.6+/-0.1 at baseline to 5.5+/-1.9 micromol x min(-1) x dl(-1), and insulin increased FGU to 1.6+/-0.3 micromol x min(-1) x dl(-1) (P<0.05 for both). The combination of ischaemia+insulin increased FGU to 15.5+/-2.2 micromol x min(-1) x dl(-1) (P<0.05 compared with each stimulus alone). Maximal FBF obtained after ischaemia was similar with and without hyperinsulinaemia. In protocol 2, isometric contraction increased FGU from 0.3+/-0.1 to 2.7+/-0.8 micromol x min(-1) x dl(-1) (P<0.05), but FGU was not significantly different from ischaemia compared with ischaemia+contraction. However, combined ischaemia+contraction resulted in a greater increase in FBF. In summary, ischaemia and insulin independently stimulate skeletal muscle glucose uptake in vivo in humans, whereas ischaemia and contraction do not. The observed differential effects of these stimuli on glucose uptake appear to be unrelated to changes in muscle blood flow.

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