The effect of glucose-insulin-potassium on thallium-201 myocardial redistribution

Intravenous infusion of glucose-insulin-potassium (GIK) has been shown to alter the net rate of clearance of 201Tl from transiently ischemic and normally perfused canine myocardium. This study was performed to determine if GIK would also decrease the extent of thallium redistribution after transient myocardial ischemia. Six anesthetized, open-chest dogs underwent two studies, one with GIK and another with saline infusion. The left anterior descending coronary artery was occluded, 201Tl injected, and the occlusion released 5-min later. An i.v. infusion of either GIK (4 dogs) or saline (2 dogs) was then begun and continued for the 120-min duration of serial myocardial imaging using a standard scintillation camera. The experiment was then repeated with an infusion of saline (4 dogs) or GIK (2 dogs). The dose of 201Tl for the second study was at least 5 times more than was used for the first study. The serial 2-min images were then displayed on computer and regions of interest were drawn over the areas of transient ischemia (TI) and normal perfusion (NP). The ratio of average counts per picture element for the area of TI compared to NP was calculated. One hundred and twenty minutes after 201Tl administration, the change in the TI/NP ratio (% fill-in) was significantly less for the GIK infusion compared to saline infusion (control) 15.4 +/- 4.0% vs 26.2 +/- 6.0% (mean +/- SE) (P less than 0.01), respectively. Therefore, GIK infusion appeared to decrease the extent of thallium redistribution compared to saline control.