The effects of repetitive stunning on regional myocardial glucose uptake in swine

Repetitive stunning may induce changes in myocardial glucose uptake (Glu) which are not apparent following a single episode of stunning. Eight swine were chronically instrumented with a hydraulic occluder on the circumflex artery (Cx). 10 min. Cx occlusion (Isch) was induced in each pig. One week later, Isch was repeated twice per day for 4 days. In the fasted state, Glu (μmol/min/g) with FDG and PET imaging and ECHO wall thickening (% Wth) were determined in Cx and remote (R) regions 24 hours following single and repetitive stunning. Myocardial blood flow (μ spheres) and plasma substrates did not differ during the two PET scans. Transmural biopsies were obtained immediately following the final scan. ATP and CP in the Cx region were 3.8±0.3 and 6.9±.1.5 μmol/g wet wt respectively and neither differed from that of R. Glycogen however, was higher in the Cx region compared with R (37± 15 vs. 28±12 nmol/mg; p<0.05). As shown in the table, Glu in the CX region was also higher than R following repetitive but not single stunning. Together with the enhanced glycogen, these data demonstrate that multiple episodes of ischemia and reperfusion induce a sustained increase in glucose uptake at a time that regional function and bioenergetics have normalized. This suggests that the myocardial adaptation to repetitive stunning involves enhanced transport and phosphorylation of glucose. Myocardial Glucose Uptake (GLU) 24 Hours Following Single (SS) and Repetitive (RS) Stunning Region Glu-SS Glu-RS %Wth-SS %Wth-RS Cx 0.22±0.18 0.34±0.16* 31±16 29±18 Remote 0.22±0.18 0.25±0.17 31±16 26±12 mean±SD; *p<0.05 vs. Remate-RS (ANOVA).