Activation of nonselective cation channels in the basolateral membrane of rat distal colon crypt cells by prostaglandin E2

Na depletion inhibits electroneutral Na-Cl absorption in intact tissues and Na/H exchange in apical membrane vesicles (AMV) of rat distal colon. Two anion (Cl/HCO3 and Cl/OH) exchanges have been identified in AMV from surface cells of rat distal colon. To determine whether Cl/HCO3 and/or Cl/OH exchange is responsible for vectorial Cl movement, this study examined the spatial distribution and the effect of Na depletion on anion-dependent 36Cl uptake by AMV in rat distal colon. These studies demonstrate that HCO3 concentration gradient-driven36Cl uptake (i.e., Cl/HCO3 exchange) is 1) primarily present in AMV from surface cells and 2) markedly reduced by Na depletion. In contrast, OH concentration gradient-driven36Cl uptake (i.e., Cl/OH exchange) present in both surface and crypt cells is not affected by Na depletion. In Na-depleted animals HCO3 also stimulates36Cl via Cl/OH exchange with low affinity. These results suggest that Cl/HCO3 exchange is responsible for vectorial Cl absorption, whereas Cl/OH exchange is involved in cell volume and/or cell pH homeostasis.

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Differential modulation of Na-HCO3 cotransport and Na-H exchange by pH in basolateral membrane vesicles of rat distal colon.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)42328-3 ◽

1994 ◽

Vol 269 (1) ◽

pp. 156-160

Author(s):

V.M. Rajendran ◽

H.J. Binder

Keyword(s):

Basolateral Membrane ◽

Membrane Vesicles ◽

Distal Colon ◽

Differential Modulation ◽

Basolateral Membrane Vesicles ◽

Rat Distal Colon

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Characterization of apical membrane Cl-dependent Na/H exchange in crypt cells of rat distal colon

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.2001.280.3.g400 ◽

2001 ◽

Vol 280 (3) ◽

pp. G400-G405 ◽

Cited By ~ 15

Author(s):

Vazhaikkurichi M. Rajendran ◽

John Geibel ◽

Henry J. Binder

Keyword(s):

Channel Blocker ◽

Apical Membrane ◽

Distal Colon ◽

Proton Gradient ◽

Disulfonic Acid ◽

High Dose ◽

Cl Channel ◽

Rat Distal Colon ◽

Na Uptake ◽

Crypt Cells

A novel Cl-dependent Na/H exchange (Cl-NHE) has been identified in apical membranes of crypt cells of rat distal colon. The presence of Cl is required for both outward proton gradient-driven Na uptake in apical membrane vesicles (AMV) and Na-dependent intracellular pH recovery from an acid load in the crypt gland. The present study establishes that Cl-dependent outward proton gradient-driven 22Na uptake 1) is saturated with increasing extravesicular Na concentration with a Michaelis constant ( K m) for Na of ∼24.2 mM; 2) is saturated with increasing outward H concentration gradient with a hyperbolic curve and a K m for H of ∼1.5 μM; 3) is inhibited by the Na/H exchange (NHE) inhibitors amiloride, ethylisopropylamiloride, and HOE-694 with an inhibitory constant ( K i) of ∼480.2, 1.1, and 9.5 μM, respectively; 4) is inhibited by 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid, an anion exchange inhibitor at low concentration and a Cl channel blocker at high dose, and by 5-nitro-2(3-phenylpropylamino)benzoic acid, a Cl channel blocker, with a K i of ∼280.6 and 18.3 μM, respectively; and 5) substantially stimulated Cl-NHE activity by dietary Na depletion, which increases plasma aldosterone and inhibits NHE in surface cell AMV. These properties of Cl-NHE are distinct from those of NHE1, NHE2, and NHE3 isoforms that are present in colonic epithelial cells; thus these results suggest that the colonic crypt cell Cl-NHE is a novel NHE isoform.

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Differential localization of colonic H+-K+-ATPase isoforms in surface and crypt cells

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1998.274.2.g424 ◽

1998 ◽

Vol 274 (2) ◽

pp. G424-G429 ◽

Cited By ~ 12

Author(s):

Vazhaikkurichi M. Rajendran ◽

Satish K. Singh ◽

John Geibel ◽

Henry J. Binder

Keyword(s):

Spatial Distribution ◽

Atpase Activity ◽

Distal Colon ◽

Compelling Evidence ◽

Α Subunit ◽

Colonic Crypts ◽

Rat Distal Colon ◽

Acid Load ◽

Apical Membranes ◽

Crypt Cells

Two distinct colonic H+-K+-adenosinetriphosphatase (H+-K+-ATPase) isoforms can be identified in part on the basis of their sensitivity to ouabain. The colonic H+-K+-ATPase α-subunit (HKcα) was recently cloned, and its message and protein are present in surface (and the upper 20% of crypt) cells in the rat distal colon. These studies were performed to establish the spatial distribution of the ouabain-sensitive and ouabain-insensitive components of both H+-K+-ATPase activity in apical membranes prepared from surface and crypt cells and K+-dependent intracellular pH (pHi) recovery from an acid load both in isolated perfused colonic crypts and in surface epithelial cells. Whereas H+-K+-ATPase activity in apical membranes from surface cells was 46% ouabain sensitive, its activity in crypt apical membranes was 96% ouabain sensitive. Similarly, K+-dependent pHi recovery in isolated crypts was completely ouabain sensitive, whereas in surface cells K+-dependent pHi recovery was insensitive to ouabain. These studies provide compelling evidence that HKcα encodes the colonic ouabain-insensitive H+-K+-ATPase and that a colonic ouabain-sensitive H+-K+-ATPase isoform is present in colonic crypts and remains to be cloned and identified.

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Bicarbonate-stimulated [14C]butyrate uptake in basolateral membrane vesicles of rat distal colon

Gastroenterology ◽

10.1016/0016-5085(93)90889-k ◽

1993 ◽

Vol 105 (3) ◽

pp. 725-732 ◽

Cited By ~ 36

Author(s):

Diedre A. Reynolds ◽

Vazhaikkurichi M. Rajendran ◽

Henry J. Binder

Keyword(s):

Basolateral Membrane ◽

Membrane Vesicles ◽

Distal Colon ◽

Basolateral Membrane Vesicles ◽

Rat Distal Colon

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Aldosterone-induced apical Na+ and K+ conductances are located predominantly in surface cells in rat distal colon

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1994.266.1.g71 ◽

1994 ◽

Vol 266 (1) ◽

pp. G71-G82 ◽

Cited By ~ 11

Author(s):

R. B. Lomax ◽

C. M. McNicholas ◽

M. Lombes ◽

G. I. Sandle

Keyword(s):

Cell Population ◽

Receptor Binding ◽

Specific Binding ◽

Distal Colon ◽

Crypt Cell ◽

K Channel ◽

Surface Cell ◽

Aldosterone Receptor ◽

Rat Distal Colon ◽

Crypt Cells

Aldosterone is a major regulator of Na(+)-absorptive and K(+)-secretory processes in the distal segment of mammalian colon. In this study, the distribution of aldosterone-sensitive cell types in isolated rat distal colon was determined using site-directed intracellular microelectrodes, specific Na(+)- and K(+)-channel blockers, and aldosterone-receptor binding techniques. Electrophysiological data indicated that aldosterone induced parallel apical membrane Na+ and K+ conductances, mainly in surface cells and to a significantly lesser degree in crypt cells. Scatchard analyses of aldosterone-receptor binding in cytosolic fractions revealed the maximum number of specific binding sites in whole mucosal homogenate and in the upper one-third and lower two-thirds of isolated crypt units to be 74.9 +/- 2.0, 59.8 +/- 2.4, and 59.3 +/- 3.2 fmol/mg protein, respectively, indicating the presence of aldosterone receptors in the crypt cell population. We conclude that in rat distal colon aldosterone-induced Na+ and K+ conductances (and by inference, electrogenic Na(+)-absorptive and K(+)-secretory processes) are located predominantly in the surface cell population and to a lesser extent in crypt cells, which also contain aldosterone receptors. This spectrum of aldosterone-induced Na+ and K+ conductances may reflect varying stages of differentiation along the surface cell-crypt cell axis.

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