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Single‐injection glucose kinetics with compartmental modelling during rest and low‐intensity exercise in horses
Author(s) -
TREIBER K. H.,
BOSTON R. C.,
GEOR R. J.,
HESS T. M.,
HARRIS P. A.,
KRONFELD D. S.
Publication year - 2010
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/j.2042-3306.2010.00239.x
Subject(s) - horse , bolus (digestion) , chemistry , medicine , kinetics , endocrinology , treadmill , physical exercise , zoology , biology , paleontology , physics , quantum mechanics
Summary Reasons for performing study: Tools and criteria to evaluate and understand glucose metabolism are essential to optimise equine energy utilisation for exercise performance and reduced metabolic health risks. Objectives: To re‐evaluate models of glucose kinetics in the horse at rest and during endurance type exercise using a single injection technique and compartmental modelling. Methods: Twelve exercise trained Arabian geldings received a bolus of 100 µmol/kg bwt [6,6‐ 2 H]glucose i.v. while at rest and while running at ∼4 m/s on a treadmill. Tracer and tracee glucose curves from 4–150 min after the bolus dose (while the subject maintained its resting or exercising state) were described by a 2 term exponential decay curve. Compartmental modelling was performed simultaneously for each horse's resting and exercise curves using an ‘exercise effect’ parameter for each compartmental exchange rate during exercise. Results: Exercise increased all rate constants and transport flows for glucose between compartments by 110–145% (P≤0.004). Total glucose transport through the system increased from 8.9 ± 0.6 µmol/min/kg/bwt at rest to 25.0 ± 1.1 µmol/min/kg bwt during exercise (P<0.001). Exercise decreased the volume of the primary glucose compartment by 8% (P = 0.006) and increased plasma glucose clearance rate by almost 200% (P<0.001). Turnover times and mean residence times were decreased approximately 60% by exercise (P<0.001), whilst turnover rates were increased 125% (P<0.001). Conclusions: Single‐injection tracer kinetics and compartmental modelling represent a valuable tool to quantify tracee availability to and use by tissue. Potential relevance: This technique could represent a beneficial tool for future studies exploring the role of glucose metabolism in equine exercise performance and metabolic disease.