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This Article Full Text Full Text (PDF) All Versions of this Article: 583/3/1069    most recent jphysiol.2007.130526v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Battram, D. S. Articles by Dela, F. Search for Related Content PubMed PubMed Citation Articles by Battram, D. S. Articles by Dela, F. Related Collections Skeletal Muscle and Exercise

¹ Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada N1G 2W1
² Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark

Caffeine (CAF) impedes insulin-mediated glucose disposal (IMGD) and increases plasma adrenaline concentrations ([ADR]; 0.6 nM). While the antagonism of ADR abolishes the CAF effect, infusion of ADR (0.75 nM) has no effect on IMGD. We have now examined CAF and ADR in concert to determine whether or not they elicit an additive response on IMGD. We hypothesized that CAF + ADR would elicit a greater effect than either CAF or ADR alone (i.e. that CAF effects would not be solely attributed to ADR). Subjects (n = 8) completed four trials in a randomized manner. An isoglycaemic–hyperinsulinaemic clamp was performed 30 min after the following treatments were administered: (1) placebo capsules and saline infusion ([ADR] = 0.29 nM) (PL trial), (2) CAF capsules (dose = 5 mg kg^–1) and saline infusion ([ADR] = 0.62 nM) (CAF trial), (3) PL capsules and ADR infusion ([ADR] = 1.19 nM) (ADR trial), and (4) CAF capsules (dose = 5 mg kg^–1) and ADR infusion ([ADR] = 0.93 nM) (CAF + ADR trial). As expected, CAF, ADR and CAF + ADR decreased (P 0.05) IMGD compared to PL. CAF + ADR resulted in a more pronounced decrease in IMGD versus PL (42%) compared to CAF (26%) or ADR (24%) alone; however, the effect was not fully additive (P = 0.08). Furthermore, CAF decreased IMGD to a similar magnitude as ADR despite a 50% lower [ADR]. In summary, while ADR contributes to the CAF-induced impairment in IMGD, it is not solely responsible for caffeine's effects.

(Received 15 February 2007; accepted after revision 20 July 2007; first published online 26 July 2007)
Corresponding author D. S. Battram: Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada N1G 2W1. Email: dbattram{at}uwo.ca