Intercompartmental fluid shifts due to glucose release during hemorrhage in rabbits

Intercompartmental fluid shifts were studied in 18 anesthetized New Zealand White rabbits after hemorrhage. During graded hemorrhage the plasma volume spontaneously replaced was proportional both in time and amount to the hyperosmolar response. This, in turn, was mainly due to hyperglycemia. In 5 fed rabbits and 5 rabbits unfed for 40 h, all subjected to 16 ml/kg of hemorrhage, plasma volume replacement was closely correlated with the hyperglycemic response. Plasma glucose concentration gradually increased in fed animals throughout a 2-h posthemorrhagic period, whereas the hyperglycemic response ceased 15 min after hemorrhage in unfed animals, and further fluid shift also stopped. During the first 30 min after hemorrhage most of the fluid that shifted into the bloodstream came from the interstitial space, as judged by a lack of change in plasma sodium and chloride concentrations. However, during the second hour of the posthemorrhagic period of well-fed rabbits, plasma sodium and chloride concentrations decreased, suggesting that dilute fluid had shifted from the cells to the interstitial space and bloodstream. We concluded that the hyperglycemic response during and after hemorrhage played a significant role in plasma volume replacement, but this was less after a period of food deprivation.