Abstract
ABSTRACT: Increased Na+/H+ exchanger activity is associated with cellular hyperplasia. Cellular hyperplasia is an adaptive response to small-intestinal resection. Therefore, we hypothesized that the small-intestinal Na+/H+ exchanger activity increases in response to small-intestinal resection. Twenty-one-d-old, male Sprague-Dawley rats were randomly divided to receive either a 70% small intestinal resection (n = 59), or a mid-small intestinal transection (n = 49). Seven d postoperatively, the animals were killed and the Na+/H+ exchanger activity of the intestinal remnants was studied by a well validated brush border membrane vesicle technique. The initial rate of Na+ uptake in the presence of an outwardly directed pH gradient and the Vmax of the amiloride-sensitive Na+ uptake were significantly increased (p < 0.01 and p < 0.001, respectively) in the resection as compared with the transection remnants and to a greater magnitude in the distal as compared with the proximal remnants. Km values were not significantly different. The amiloride-sensitive Na+ uptake in the setting of various intravesicular pH was significantly greater (p < 0.001) in the distal resection as compared with the distal transection remnants, with points of enhanced Na+/H+ exchanger activity of intravesicular pH 6.62 and 6.87, respectively. The presence and activation of the Na+/H+ exchanger's internal modifier site was confirmed by demonstrating the effect of intravesicular pH on Na+ efflux. The present study demonstrates an up-regulation of intestinal Na+/H+ exchange activity in a small-bowel resection model in the weanling rat. This adaptive increase in Na+/H+ exchange activity is secondary to an increase in the Vmax of the intestinal Na+/H+ exchanger and is associated with a shift in the sensitivity of its internal modifier site. This adaptive response may play a role in the cellular hyperplasia in small-bowel resection
Similar content being viewed by others
Article PDF
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Sacks, A., Acra, S., Dykes, W. et al. Intestinal Na+/H+ Exchanger Activity is Up-Regulated by Bowel Resection in the Weanling Rat. Pediatr Res 33, 215–220 (1993). https://doi.org/10.1203/00006450-199303000-00001
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1203/00006450-199303000-00001
This article is cited by
-
Artificial versus natural surfactant — Can we base clinical practice on a firm scientific footing?
European Journal of Pediatrics (1994)