In birds, NHE2 is major brush-border Na+/H+ exchanger in colon and is increased by a low-NaCl diet.

We previously reported that mammalian small intestinal and colonic brush borders (BBs) contained both epithelial Na+/H+ exchangers NHE2 and NHE3. We now show that, in the avian (chicken) colon, NHE2 is the major functional isoform under basal conditions and when stimulated by a low-NaCl diet. Hubbard chickens were maintained for 2 wk on a high- or low-NaCl diet. After the chickens were killed, the ileum and colon were removed, and BBs were prepared by Mg2+ precipitation and 22Na and D-[14C]glucose uptake determined in the BB vesicles. NHE2 and NHE3 were separated by differential sensitivity to HOE-694 (NHE2 defined as Na+/H+ exchange inhibited by 50 microM HOE-694). Chickens on a low-Na+ diet have increased plasma aldosterone (10 vs. 207 pg/ml). On the high-NaCl diet, both NHE2 and NHE3 contributed to ileal and colonic apical Na+/H+ exchange, contributing equally in ileum, but NHE2 being the major component in colon (86%). Low-NaCl diet significantly increased ileal and colonic BB Na+/H+ exchange; the increase in BB Na+/H+ exchange in both ileum and colon was entirely due to an increase in NHE2 with no change in NHE3 activity. In contrast, low-NaCl diet decreased ileal and colonic Na+-dependent D-glucose uptake. Western analysis showed that low-Na+ diet increased the amount of NHE2 in the ileal and colonic BB and decreased the amount of ileal Na+-dependent glucose transporter SGLT1. Both NHE2 and NHE3 were present in the apical but not basolateral membranes (BLM) of ileal and colonic epithelial cells. In summary, 1) NHE2 and NHE3 are both present in the BB and not BLM of chicken ileum and colon; 2) NHE2 is the major physiological colonic BB Na+/H+ exchanger under basal conditions; 3) low-NaCl diet, which increases plasma aldosterone, increases ileal and colonic BB Na+/H+ exchange and decreases Na+-dependent D-glucose uptake; 4) the stimulation of colonic BB Na+/H+ exchange is due to increased activity and amount of NHE2; and 5) the inhibition of ileal D-glucose uptake is associated with a decrease in SGLT1 amount. NHE2 is the major chicken colonic BB Na+/H+ exchanger.

[1]  M. Danson,et al.  Citrate synthase. , 2020, Current topics in cellular regulation.

[2]  Fermín Sánchez de Medina,et al.  Quantitative contribution of NHE2 and NHE3 to rabbit ileal brush-border Na+/H+exchange. , 1998, American journal of physiology. Cell physiology.

[3]  S. Shirazi-Beechey,et al.  Expression of the Na+/glucose co-transporter (SGLT1) along the length of the avian intestine. , 1997, Biochemical Society Transactions.

[4]  M. L. Calonge,et al.  Na+-H+ exchange and intracellular pH regulation in colonocytes from the chick. , 1997, Biochimica et Biophysica Acta.

[5]  M. Kashgarian,et al.  Regulation of colonic H-K-ATPase in large intestine and kidney by dietary Na depletion and dietary K depletion. , 1997, The American journal of physiology.

[6]  M. L. Calonge,et al.  Apical ouabain-sensitive K+-activated-ATPase activity in colon and caecum of the chick , 1996, Pflügers Archiv.

[7]  T. Layden,et al.  Intestinal distribution of human Na+/H+ exchanger isoforms NHE-1, NHE-2, and NHE-3 mRNA. , 1996, The American journal of physiology.

[8]  J. Pouysségur,et al.  Differential localization of Na+/H+ exchanger isoforms (NHE1 and NHE3) in polarized epithelial cell lines. , 1996, Journal of cell science.

[9]  S. Gribble,et al.  Factors and molecular mechanisms involved in the regulation of chicken colonic luminal membrane Na(+)-linked transport systems. , 1996, Biochemical Society Transactions.

[10]  S. Shirazi-Beechey,et al.  Amino acid sequence and the cellular location of the Na(+)-dependent D-glucose symporters (SGLT1) in the ovine enterocyte and the parotid acinar cell. , 1995, The Biochemical journal.

[11]  A. Ilundain,et al.  Na(+)-H(+) exchange activity in brush-border membrane vesicles isolated from chick small intestine. , 1995, Biochimica et Biophysica Acta.

[12]  M. Donowitz,et al.  Na+/H+ exchanger-2 is an O-linked but not an N-linked sialoglycoprotein. , 1994, Biochemistry.

[13]  M. Donowitz,et al.  Brush-border tyrosine phosphorylation stimulates ileal neutral NaCl absorption and brush-border Na(+)-H+ exchange. , 1994, American Journal of Physiology.

[14]  J. Pouysségur,et al.  Pharmacological characterization of stably transfected Na+/H+ antiporter isoforms using amiloride analogs and a new inhibitor exhibiting anti-ischemic properties. , 1993, Molecular pharmacology.

[15]  S. Shirazi-Beechey,et al.  Regulation of sugar transport in chicken enterocytes. , 1993, Biochemical Society Transactions.

[16]  G. Shull,et al.  Primary structure and functional expression of a novel gastrointestinal isoform of the rat Na/H exchanger. , 1993, Journal of Biological Chemistry.

[17]  S. Brant,et al.  Glucocorticoid stimulation of ileal Na+ absorptive cell brush border Na+/H+ exchange and association with an increase in message for NHE-3, an epithelial Na+/H+ exchanger isoform. , 1993, The Journal of biological chemistry.

[18]  T. Mayhew,et al.  Quantitative analysis of factors contributing to expansion of microvillous surface area in the coprodaeum of hens transferred to a low NaCl diet. , 1992, Journal of anatomy.

[19]  E. Wright,et al.  Molecular evidence for two renal Na+/glucose cotransporters. , 1992, Biochimica et biophysica acta.

[20]  J. D. del Castillo,et al.  Apical membrane localization of ouabain-sensitive K(+)-activated ATPase activities in rat distal colon. , 1991, The American journal of physiology.

[21]  V. Dantzer,et al.  Aldosterone modulates electrogenic Cl secretion in the colon of the hen (Gallus domesticus). , 1991, The American journal of physiology.

[22]  M. L. Calonge,et al.  Glycylsarcosine transport by epithelial cells isolated from chicken proximal cecum and rectum. , 1990, The American journal of physiology.

[23]  S. Shirazi-Beechey,et al.  Preparation and properties of brush-border membrane vesicles from human small intestine. , 1990, Gastroenterology.

[24]  F. DeRubertis,et al.  Role of activation of protein kinase C in the stimulation of colonic epithelial proliferation by unsaturated fatty acids. , 1988, Gastroenterology.

[25]  O. Olsen,et al.  Effects of sugars, amino acids and inhibitors on electrolyte transport across hen colon at different sodium chloride intakes. , 1980, The Journal of physiology.

[26]  O. Olsen,et al.  Effects of dietary intake of sodium chloride on sugar and amino acid transport across isolated hen colon , 1980, The Journal of physiology.

[27]  M. Nesheim,et al.  The digestion of heat-damaged protein , 1967, British Journal of Nutrition.

[28]  H. Garty,et al.  Cloning and induction by low NaCl intake of avian intestine Na+ channel subunits. , 1997, The American journal of physiology.

[29]  P. Wilson,et al.  NHE2 and NHE3 are human and rabbit intestinal brush-border proteins. , 1996, The American journal of physiology.

[30]  E. Skadhauge.  Basic Characteristics and Hormonal Regulation of Ion Transport in Avian Hindguts , 1993 .

[31]  V. Dantzer,et al.  Regulation of electrogenic Na-absorption and induced Cl-secretion in an intestinal epithelium: delayed effects of aldosterone. , 1989, Acta physiologica Scandinavica. Supplementum.

[32]  E. Skadhauge,et al.  Modulation of Na and Cl transport by mineralocorticoids. , 1988, Comparative biochemistry and physiology. A, Comparative physiology.

[33]  D. H. Thomas,et al.  Aldosterone effects on electrolyte transport of the lower intestine (coprodeum and colon) of the fowl (Gallus domesticus) in vitro. , 1980, General and comparative endocrinology.

[34]  P. Srere,et al.  [1] Citrate synthase. [EC 4.1.3.7. Citrate oxaloacetate-lyase (CoA-acetylating)] , 1969 .

[35]  A. Dahlqvist,et al.  METHOD FOR ASSAY OF INTESTINAL DISACCHARIDASES. , 1964, Analytical biochemistry.