The temporal characteristics of the metabolic and endocrine response to injury

The neuroendocrine and substrate responses immediately after injury have been extensively investigated in man and animals. The purpose of the present study was to examine simultaneously, the temporal, metabolic and endocrine consequences of a single uniform injury induced by the injection of lambda-carrageenan into the hindlimbs of male Sprague-Dawley rats and to compare this response to that observed in semistarved pair-fed control animals. Immediately after injury there was a decrease in the plasma hematocrit, increase in tissue water and peripheral vasoconstriction that suggested hypovolemia. This was followed by a restoration of the blood volume by 1 day as reflected in hemodilution. Alterations in insulin, glucagon, ACTH, corticosterone, epinephrine, norepinephrine, and dopamine in wounded animals occurred during the first 5 days. However, similar changes were observed in pair-fed control animals from days 1 to 5. These findings implied that the early endocrine response observed from 0 to 24 hours after injury arises, primarily as a result of hypovolemia, whereas the response observed from 1 to 5 days appeared to be the result of semistarvation. In contrast to the endocrine alterations observed, alterations in the plasma concentrations of lactate, acetoacetate and beta-hydroxybutyrate persisted for up to 15 days. The presence of these substrate alterations in the absence of hormonal stimuli suggest that nonendocrine mechanisms exist to induce these alterations. The possibility is raised that these substrate alterations may be, at least in part, the result of the inflammatory infiltrate.