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Cardiovascular: Basic ScienceSmall Animal Imaging |
1 Albert Einstein College of Medicine, Bronx, New York; 2 Peking Unversity, Fujian Medical University, Beijing, Fuzhou, China
128
Objectives: Cardiac F-18 fluorodeoxyglucose (FDG) activity in human PET scans is variable despite efforts to standardize protocols. Heart uptake can obscure chest disease, but is also of physiologic interest since heart can metabolize fatty acids, ketone bodies as well as glucose, while brain glucose uptake uses insulin-independent transporters. It would be valuable to understand cardiac and brain FDG dependence on dietary manipulation. Long-term (1) & even short-term CHO restriction (2) can reduce heart FDG uptake. We hypothesize that very low CHO (LC) diets reduce tonic insulin response resulting in lower FDG heart uptake compared with high and intermediate CHO (HC & IC) diets; & test our hypothesis in a rodent model.
Methods: 15 Wistar rats (age 6-8 wks) were randomized to 3 diet groups (n= 5) of LC (0.1% of total energy), IC (52%) and HC (78%) content (3), keeping protein and Calories constant. After 4 wks, blood for ketone bodies, glucose, insulin and glucagon was stored for analysis, followed by MicroPET within 2 days. Images were obtained under anesthesia after a 3 hr fast. Each rat received 600 uCi FDG by tail vein, followed in 1 hr by whole body PET for 10 min on a Concorde R4 scanner. Heart and brain regions of interest (ROIs) determined SUVmax. Mean±SD SUVmax (MSUV)were compared using ANOVA among all comparisons.
Results: Heart MSUV was 3.2±1.2 (LC); 10.6±2.5 (IC); 10.6±2.8(HC); p<0.0001 for LC but p = NS for IC vs. HC. Brain values MSUV = 4.2±0.7 (LC), 3.9±0.6 (IC), 3.5±0.7 (HC) did not differ with diet (p = NS) .
Conclusions: This prospective study demonstrates reduced cardiac, but stable brain uptake of FDG in chronic VLC diets, consistent with differing insulin sensitivity of GLUT transporters in these organs.
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