Hepatic glucokinase activity and circulating insulin concentrations in two inbred mouse strains.

Hepatic glucokinase activity in the C3H/He strain of mice is about twice that in the C58 strain. Genetic analysis of hybrids and back-crosses indicates control of activity by a single codominant gene. The adaptations of activity that occur when animals of the two strains are starved, fed a carbohydrate-free diet or made streptozotocin-diabetic are similar in the two strains. In almost all the situations tested, plasma insulin concentrations were higher in the C3H/He strain than in the C58 strain. On the assumption that insulin plays some role in the synthesis of glucokinase, the possible association between the plasma insulin concentration and hepatic glucokinase activity in mice in which plasma glucose concentrations are similar is discussed. The twofold difference in glucokinase activity between the two strains is associated with only minor differences in glucose tolerance and insulin response to a glucose load.