Variability of insulin-stimulated myocardial glucose uptake in healthy elderly subjects.
The aim of this study was to assess regional and global variability of insulin-stimulated myocardial glucose uptake in healthy elderly subjects and to evaluate potentially responsible factors. Twenty men with a mean age of 64 years, no history of cardiovascular disease, and normal blood pressure, bicycle exercise test, electrocardiogram and echocardiography were studied [ P(coronary artery disease) <5%]. Whole-body insulin sensitivity and insulin-stimulated myocardial glucose uptake were measured during hyperinsulinaemic euglycaemic glucose clamp with fluorine-18 fluorodeoxyglucose, and myocardial rest and hyperaemic blood flow during dipyridamole infusion were measured with nitrogen-13 ammonia and positron emission tomography in 16 left ventricular myocardial segments. Intra-individual and inter-individual variability of insulin-stimulated myocardial glucose uptake [relative dispersion = (standard deviation/mean)] was 13% and 29% respectively. Although inter-individual variability of glucose uptake and blood flow at rest was of the same magnitude, no correlation was found between these measures. Regional and global insulin-stimulated myocardial glucose uptake correlated linearly with whole-body insulin sensitivity ( r=0.51, P<0.05 and r=0.56, P<0.01). The strongest independent association by multivariate linear regression analysis was found between myocardial glucose uptake and hyperaemic blood flow ( r=0.63, P<0.005). We conclude that in healthy elderly subjects, insulin-stimulated myocardial glucose uptake is homogeneous throughout the left ventricle, but has moderate inter-individual variability. Inter-individual variability of insulin-stimulated myocardial glucose uptake is primarily explained by variability in coronary vascular reactivity and tissue insulin sensitivity.
Kofoed
Klaus F
KF
Cardiovascular PET Research Unit, Section 9201, Medical Department B, The Heart Center, Rigshospitalet, University of Copenhagen, Juliane Mariesvej 24, 2100 Copenhagen, Denmark. kkofoed@pet.rh.dk
Hove
Jens D
JD
Freiberg
Jacob
J
Høst
Ulla
U
Holm
Søren
S
Kelbaek
Henning
H
D000641:Ammonia / Q000493:pharmacokinetics; D001786:Blood Glucose / Q000032:analysis; D004176:Dipyridamole; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D005947:Glucose / Q000493:pharmacokinetics*; D015309:Glucose Clamp Technique / Q000379:methods; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D006940:Hyperemia / Q000139:chemically induced; D006946:Hyperinsulinism / Q000139:chemically induced; D007328:Insulin / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D009590:Nitrogen Radioisotopes / Q000493:pharmacokinetics; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution; D014055:Tomography, Emission-Computed / Q000379:methods*; D016277:Ventricular Function, Left
D001786:Blood Glucose; D007328:Insulin; D009590:Nitrogen Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D004176:Dipyridamole; D000641:Ammonia; D005947:Glucose