INSULIN RELEASE DURING ACUTE AND CHRONIC HYPOXIA

Glucose-induced insulin release was studied in 6 month old puppies during acute and chronic hypoxia, alone and in combination. Six experimental animals were rendered chronically hypoxic (PaO2 ∼ 40 torr) by creation of a R → L shunt at age 1½ months. Six control animals (PaO2>70 torr) underwent sham procedures at the same age. Acute hypoxia (AH)(PaO2 ∼ 20 torr) was produced in both control and experimental animals by ventilation with 8 or 10% oxygen. All experiments included glucose pulses (.25 gm/kg) given during ventilation with room air and with low oxygen mixtures. Tabulated below are the mean increases in plasma glucose and plasma insulin in each group. Only significant differences are indicated.These data indicate that chronically hypoxic animals have an insulin response to glucose challenge equivalent to controls. The diminished insulin response seen in acutely hypoxlc animals is not prevented by chronic hypoxia. Since insulin is crucial for fuel metabolism, these observations are relevant to heat and energy production in children with cyanotic congenital heart disease who encounter situations which acutely impose further oxygen deficiency.