HORMONAL DERANGEMENT AND ABNORMAL RENAL HAEMODYNAMICS IN THE ACUTE PHASE OF SEVERE BURNS IN RATS

Abstract

A severe burn is characterized by the development of hyperenzymatic levels in plasma and biochemical changes in 
the blood as well as generalized hormonal dysregulation. This hypercatabolic state reflects the generalized enhanced 
proteolytic enzyme systems following severe burns. Since anuria often develops in the first hour following severe 
burns, we investigated the role of renal vasoactive peptides in the early events following severe scalding in order to 
know the extent of their involvement in the pathogenesis of deranged renal function. Male Wistar rats weighing 200 
to 300 g were subjected to a 25% surface area burn by immersing their shaved dorsal surface in water at 70°C for 60 
seconds under pentobarbital anaesthesia. A reduction in urinary kallikrein excretion was found (P<0.05) while the 
renal cortex kallikrein activity remained normal one hour after scalding. An increase in plasma renin activity (P<0.05) 
and a marked increase in plasma beta-endorphin concentration (P<0.005) was observed. Blood pressure was 
reduced in the experimental group (P<0.05). Hematocrit levels were elevated (P<0.001) and haemoglobinuria was 
evident in the first one hour. Plasma proteins remained unchanged. A significant reduction of urine volume was 
observed in the first hour (P<0.01). Plasma potassium was elevated (P<0.001) and its urinary excretion was reduced 
(P<0.01). The high plasma renin activity and the enhanced plasma concentration of beta-endorphin suggest that in 
the first hour following severe burns, hormonal derangements are mainly responsible for abnormal renal 
hemodynamics.