Myocardial Hibernation in the Absence of Augmented Glucose Metabolism in Swine Hearts.

It has been proposed that a shift to glucose as a metabolic substrate plays an important role in the protection against ischemia in hibernating myocardium. This possibility was evaluated in eight pigs, which were chronically instrumented to measure coronary blood flow (CBF), regional wall thickening (WT), and myocardial glucose uptake (MGU). The animals were divided into control (CON; n=4) and streptozotocin‐treated (STZ, 75 mg/kg; n=4) groups. Persistent myocardial stunning leading to hibernation was induced by six repetitive episodes of 90‐min coronary stenosis (CS) (30% reduction in baseline CBF) followed by full reperfusion every 12 hrs. Plasma glucose was elevated in STZ group compared to CON (573±98 vs. 100±3 mg/dl). MGU was increased 2‐fold in CON group during 1 st CS (and remained elevated during entire stunning protocol), whereas there was no change in MGU in STZ group. Nevertheless, the decreases in AWT in CON and STZ groups during 1st CS were similar (−46±10% vs. −36±7%, respectively), as were those just prior to 6th CS (−28±9% and −21±10%, respectively). In similarity to CON group, STZ group showed no decrease in WT during 6 th CS. We conclude that diabetes did not alter the changes in myocardial contractile function during repetitive episodes of ischemia, and that an augmented glucose metabolism was not necessary for protection against ischemia in hibernating myocardium.