Effect of burn injury on intestinal Na+/H+ exchangers

The Na+/H+ exchangers at the brush border membrane (BBM) and the basolateral membrane (BLM) are each distinct with different kinetic and pharmacologic characteristics. At the BBM, Na+/H+ exchange provides an acid microenvironment necessary for nutrient transport. At the BLM, the Na+/H+ exchanger regulates intracellular pH and cell volume which affect cell growth and repair. This study was designed to determine the effect of burn injury on Na+/H+ exchange at the BBM and BLM of the rat enterocyte. Adolescent Sprague-Dawley rats were divided into control (n = 6) and 20% scald burn groups (n = 6). Using differential centrifugation and percoll density gradient techniques, BBM and BLM vesicles were prepared from the jejunum. 22Na+ uptake was measured using a rapid filtration technique. Initial rate uptake studies showed that the slope of Na+ uptake in BBM (y = 0.06x + 0.12, r2 = 0.99) and BLM (y = 0.075x + 0.1, r2 = 0.99) of the control group was higher (P < 0.05) than that in the burn group (y = 0.0345x + 0.06, r2 = 0.98 and y = 0.056x + 0.01, r2 = 0.99). To determine whether the changes in transport are related to the feeding pattern in burn rats, similar experiments were done in pair-fed animals. The initial rate uptake studies of BBM showed a similarily greater slope of Na+ uptake in pair-fed control animals compared to the burn group (y = 0.043x + 0.06, r2 = 0.99 and y = 0.062x + 0.008, r2 = 0.98; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)