Obesity affects myocardial vasoreactivity and coronary flow response to insulin.
OBJECTIVE
Obesity is associated with increased risk for cardiovascular diseases and peripheral endothelial dysfunction. We examined whether myocardial vasoreactivity and coronary-flow response to insulin stimulation are altered in obesity.


METHODS
Myocardial blood flow was quantitated in 10 obese men (body mass index, 33.6 +/- 1.9 kg/m(2)) and 10 healthy matched non-obese men (body mass index, 24.2 +/- 1.9 kg/m(2)), using positron emission tomography and oxygen-15-labeled water. The measurements were performed basally and during adenosine infusion (140 microg/kg per minute), with or without simultaneous physiological (1 mU/kg per minute) and supraphysiological (5 mU/kg per minute) hyperinsulinemia.


RESULTS
Basal myocardial blood flow was not significantly different between obese and non-obese subjects. Adenosine-stimulated flow was blunted in obese (3.2 +/- 0.6 mL/g per minute) when compared with non-obese subjects (4.0 +/- 1.1 mL/g per minute, p < 0.05). Simultaneous physiological hyperinsulinemia increased adenosine-stimulated myocardial flow significantly in both groups (to 4.03 +/- 1.24 and 4.85 +/- 1.04 mL/g per minute in obese and non-obese men, respectively; p < 0.05 vs. adenosine). Supraphysiological hyperinsulinemia further enhanced the adenosine-stimulated flow in non-obese subjects (to 5.56 +/- 0.98 mL/g per minute; p < 0.05) but not in obese subjects.


CONCLUSIONS
Young obese, healthy men have reduced myocardial vasoreactivity, which may represent an early precursor of future coronary artery disease. Additionally, insulin-induced enhancement of myocardial blood flow is blunted in obesity. Thus, endothelial dysfunction seems to also characterize myocardial vasculature of obese subjects.
Sundell
Jan
J
Turku PET Centre, Department of Medicine, Turku University, Turku, Finland. jan.sundell@utu.fi
Laine
Hanna
H
Luotolahti
Matti
M
Kalliokoski
Kari
K
Raitakari
Olli
O
Nuutila
Pirjo
P
Knuuti
Juhani
J
D000241:Adenosine / Q000008:administration & dosage; D000328:Adult; D001783:Blood Flow Velocity; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure; D001823:Body Composition; D015992:Body Mass Index; D003326:Coronary Circulation / Q000187:drug effects*; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate; D006801:Humans; D006946:Hyperinsulinism; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D009765:Obesity / Q000503:physiopathology*; D010104:Oxygen Radioisotopes; D014055:Tomography, Emission-Computed; D014867:Water
D001786:Blood Glucose; D007328:Insulin; D010104:Oxygen Radioisotopes; D014867:Water; D000241:Adenosine