Effect of transient ischemia on the expression of glucose transporters GLUT-1 and GLUT-4 in rat myocardium

A number of observations indicate that myocardial glucose utilization is in creased late during post-ischemic reperfusion. The present study was design ed to examine whether transient ischemia elicits altered expression of gluc ose transporters GLUT-1 and GLUT-4. In rats, the left anterior descending c oronary artery was occluded for 20 min followed by reperfusion for 1, 3 or 7 days. Regional myocardial uptake and phosphorylation of glucose was deter mined based on myocardial accumulation of 2-deoxy-D-[2,6-H-3]glucose-6-phos phate. In hearts from fasted rats, after 3 days of reperfusion, myocardial uptake and phosphorylation of glucose was 48% higher in the reperfused region comp ared to a remote control region. No regional difference in myocardial gluco se uptake and phosphorylation was delectable in hearts from fed rats. After 1 day of reperfusion, expression of myocardial glucose transporter GLUT-1 mRNA was increased to 195 +/- 24% (mean +/- SEM) of the Value measured in t he remote region and the expression of GLUT-4 mRNA was decreased to 58 +/- 7%. After 3 days of reperfusion both mRNA and protein of GLUT-1 were higher in the reperfused region. averaging 133 +/- 23% and 249 +/- 36%, respectiv ely. The corresponding values for GLUT-4 mRNA and protein were 77 +/- 7% an d 62 +/- 6%, respectively. The results indicate that a short period of isch emia alters the expression of glucose transporter isoforms GLUT-1 and GLUT- 4. Observed changes may be involved in the mechanisms underlying late chang es of substrate metabolism during reperfusion. (C) 1999 Academic Press.