The relationship of glucagon and insulin to sequential changes in metabolic fuel utilization in shock

Previous studies in the dog have demonstrated significant alterations in the mobilization of metabolic fuel during shock. In particular, mobilization of depot fat is markedly depressed. The present study examines the sequential utilization of nonlipid fuels over a 24-hr shock period. Metabolic rates were unchanged from controls. Skeletal muscle glycogen fell exponentially from 7.0 ± 0.5 to 2.7 ± 0.2 mg/g (P < 0.001) after 24 hr of shock. Protein breakdown as reflected by urea production was linear throughout the period and increased 50% over controls (P < 0.001). Lactate levels did not reflect changes in metabolic rate but fell to nearly normal levels once muscle glycogen was depleted. The contribution of CHO and protein combined to CO₂ production fell from 70% in early shock to 42% in the final 12 hr of the 24-hr shock period. This compares to 23% in controls. Protein catabolism alone accounted for an average of 32% of CO₂ production in shock. While insulin levels rose slightly in early shock and then fell, glucagon rose rapidly in the first 5 hr of shock and then remained significantly and constantly elevated throughout the entire shock period. The insulin-glucagon molar ratio remained in the severely catabolic range throughout.