Effect of adrenaline on glucose kinetics during exercise in adrenalectomised humans.
Level 3 - non-randomized controlled study
Non-randomized matched controlled physiological study
PubMed 10457100 · doi:10.1111/j.1469-7793.1999.0911n.x
What was done
Six bilaterally adrenalectomised, adrenaline-deficient individuals and six sex- and age-matched healthy controls were studied during cycling exercise (45 min at 68 ± 1% VO2,max followed by 15 min at 84 ± 2% VO2,max). Adrenalectomised subjects performed the protocol without (-ADR) or with (+ADR) an adrenaline infusion that elevated plasma adrenaline to 4.49 ± 0.69 nmol/l at 45 min and 12.41 ± 1.80 nmol/l at 60 min. Glucose kinetics were measured using a [3-3H]glucose tracer alongside circulating hormones and metabolites.
What was found
Euglycaemia was maintained during exercise in controls and in adrenalectomised subjects without adrenaline (-ADR), whereas plasma glucose increased in +ADR. The overall exercise-induced increase in hepatic glucose production was similar between +ADR and -ADR, though adrenaline infusion augmented the rise early in exercise. Muscle glucose uptake increased during exercise in both conditions but was lower, with a reduced metabolic clearance rate, in +ADR. Noradrenaline and glucagon increased while insulin and cortisol decreased similarly across trials. Adrenaline infusion suppressed growth hormone and increased free fatty acids, glycerol, and lactate, while alanine and beta-hydroxybutyrate remained similar.
Why it matters
Adrenaline is not required to maintain euglycaemia or match hepatic glucose output to peripheral uptake during moderate-to-intense exercise. Elevated adrenaline instead drives hyperglycaemia by simultaneously accelerating early hepatic glucose production and impairing glucose clearance.
Limits
The study is limited by a small sample size (n = 6 adrenalectomised subjects and n = 6 controls) and a specialized surgical population. Exact numeric values for glucose kinetics, uptake rates, and baseline hormone levels were not detailed in the abstract.
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