Intestinal Na+/H+ exchanger activity is up-regulated by bowel resection in the weanling rat

A. I. Sacks, S. A. Acra, W. Dykes, D. B. Polk, J. A. Barnard, J. Pietsch, Fayez K Ghishan

Research output: Contribution to journalArticle

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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 V(max) 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 V(max) 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.

Original languageEnglish (US)
Pages (from-to)215-220
Number of pages6
JournalPediatric Research
Volume33
Issue number3
StatePublished - 1993
Externally publishedYes

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Sodium-Hydrogen Antiporter
Hyperplasia
Amiloride
Proton-Motive Force
Microvilli
Sprague Dawley Rats
Up-Regulation
Membranes

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health

Cite this

Sacks, A. I., Acra, S. A., Dykes, W., Polk, D. B., Barnard, J. A., Pietsch, J., & Ghishan, F. K. (1993). Intestinal Na+/H+ exchanger activity is up-regulated by bowel resection in the weanling rat. Pediatric Research, 33(3), 215-220.

Intestinal Na+/H+ exchanger activity is up-regulated by bowel resection in the weanling rat. / Sacks, A. I.; Acra, S. A.; Dykes, W.; Polk, D. B.; Barnard, J. A.; Pietsch, J.; Ghishan, Fayez K.

In: Pediatric Research, Vol. 33, No. 3, 1993, p. 215-220.

Research output: Contribution to journalArticle

Sacks, AI, Acra, SA, Dykes, W, Polk, DB, Barnard, JA, Pietsch, J & Ghishan, FK 1993, 'Intestinal Na+/H+ exchanger activity is up-regulated by bowel resection in the weanling rat', Pediatric Research, vol. 33, no. 3, pp. 215-220.
Sacks AI, Acra SA, Dykes W, Polk DB, Barnard JA, Pietsch J et al. Intestinal Na+/H+ exchanger activity is up-regulated by bowel resection in the weanling rat. Pediatric Research. 1993;33(3):215-220.
Sacks, A. I. ; Acra, S. A. ; Dykes, W. ; Polk, D. B. ; Barnard, J. A. ; Pietsch, J. ; Ghishan, Fayez K. / Intestinal Na+/H+ exchanger activity is up-regulated by bowel resection in the weanling rat. In: Pediatric Research. 1993 ; Vol. 33, No. 3. pp. 215-220.
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AU - Acra, S. A.

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AU - Polk, D. B.

AU - Barnard, J. A.

AU - Pietsch, J.

AU - Ghishan, Fayez K

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N2 - 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 V(max) 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 V(max) 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.

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