Determination of Glucose Utilization in the Dog with [2- 3 H],[6- 3 H]-,and [U- 14 C]Glucose 1

Summary

Parameters of in vivo glucose metabolism in adult female dogs fasted for 48 hr were estimated after a single injection of [2-³H]- or [6-³H]glucose in combination with [U-¹⁴C]glucose. The glucose replacement rate estimated with [2-³H]glucose averaged 4.6 mg/min/kg and was about 25% higher than the values obtained with [6-³H]glucose. Estimates of glucose-carbon recycling were more than twice as high (31 vs 14%) when [2-³H]glucose was utilized as tracer than when [6-³H]glucose was utilized. These differences suggest the presence of a “futile” cycle between glucose and glucose-6-phosphate in the dog.