Abnormal in vivo myocardial energy substrate uptake in diet-induced type 2 diabetic cardiomyopathy in rats.
The purpose of this study was to determine in vivo myocardial energy metabolism and function in a nutritional model of type 2 diabetes. Wistar rats rendered insulin-resistant and mildly hyperglycemic, hyperinsulinemic, and hypertriglyceridemic with a high-fructose/high-fat diet over a 6-wk period with injection of a small dose of streptozotocin (HFHFS) and control rats were studied using micro-PET (microPET) without or with a euglycemic hyperinsulinemic clamp. During glucose clamp, myocardial metabolic rate of glucose measured with [(18)F]fluorodeoxyglucose ([(18)F]FDG) was reduced by approximately 81% (P < 0.05), whereas myocardial plasma nonesterified fatty acid (NEFA) uptake as determined by [(18)F]fluorothia-6-heptadecanoic acid ([(18)F]FTHA) was not significantly changed in HFHFS vs. control rats. Myocardial oxidative metabolism as assessed by [(11)C]acetate and myocardial perfusion index as assessed by [(13)N]ammonia were similar in both groups, whereas left ventricular ejection fraction as assessed by microPET was reduced by 26% in HFHFS rats (P < 0.05). Without glucose clamp, NEFA uptake was approximately 40% lower in HFHFS rats (P < 0.05). However, myocardial uptake of [(18)F]FTHA administered by gastric gavage was significantly higher in HFHFS rats (P < 0.05). These abnormalities were associated with reduced Glut4 mRNA expression and increased Cd36 mRNA expression and mitochondrial carnitine palmitoyltransferase 1 activity (P < 0.05). HFHFS rats display type 2 diabetes complicated by left ventricular contractile dysfunction with profound reduction in myocardial glucose utilization, activation of fatty acid metabolic pathways, and preserved myocardial oxidative metabolism, suggesting reduced myocardial metabolic efficiency. In this model, increased myocardial fatty acid exposure likely occurs from circulating triglyceride, but not from circulating plasma NEFA.
Division of Endocrinology, Department of Medicine, University de Sherbrooke, Sherbrooke, QC, Canada.
Sébastien L
SL
Ménard
Etienne
E
Croteau
Otman
O
Sarrhini
Roselle
R
Gélinas
Pascal
P
Brassard
René
R
Ouellet
M'hamed
M
Bentourkia
Johannes E
JE
van Lier
Christine
C
Des Rosiers
Roger
R
Lecomte
André C
AC
Carpentier
D000704:Analysis of Variance; D000818:Animals; D009202:Cardiomyopathies / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005947:Glucose / Q000378:metabolism*; D015309:Glucose Clamp Technique; D006321:Heart / Q000000981:diagnostic imaging; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism; D007328:Insulin / Q000097:blood; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D011877:Radionuclide Imaging; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014280:Triglycerides / Q000097:blood
D005230:Fatty Acids, Nonesterified; D007328:Insulin; D014280:Triglycerides; D005947:Glucose