Diabetes, Vol 30, Issue 11 923-928, Copyright © 1981 by American Diabetes Association
Adaptation of glycolytic enzymes: glucose use and insulin release in rat pancreatic islets during fasting and refeeding
PT Burch, MD Trus, DK Berner, A Leontire, KC Zawalich and FM Matschinsky
Starvation refeeding experiments were conducted in rats to test the
hypothesis that adaptation of glucokinase (the high Km component of glucose
phosphorylation) could be the major determinant of glucose metabolism of
pancreatic islet cells and of glucose-stimulated insulin release. It was
found that glucokinase of islet homogenates, glucose use by intact isolated
islets, and glucose-induced insulin release as studied in a perifusion
system were decreased after 24 h of fasting, whereas P-fructokinase and
3-P-glyceraldehyde DH were unaltered. After extended fasting (e.g., 120 h)
all three enzymes were decreased but glucose use did not change any
further. Refeeding normalized all parameters. These and previous results
support the concept that glucokinase serves as the adaptive beta-cell
glucoreceptor relating blood glucose to insulin release.