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

1998 ◽  
Vol 274 (2) ◽  
pp. G424-G429 ◽  
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.

Distribution and regulation of apical Cl/anion exchanges in surface and crypt cells of rat distal colon

1999 ◽  
Vol 276 (1) ◽  
pp. G132-G137 ◽  
Author(s):  
Vazhaikkurichi M. Rajendran ◽  
Henry J. Binder
Keyword(s):  
Spatial Distribution ◽  
Concentration Gradient ◽  
Apical Membrane ◽  
Membrane Vesicles ◽  
Distal Colon ◽  
Ph Homeostasis ◽  
Rat Distal Colon ◽  
Na Depletion ◽  
Crypt Cells ◽  
Apical Membrane Vesicles

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.

Apical membrane localization of ouabain-sensitive K(+)-activated ATPase activities in rat distal colon

1991 ◽  
Vol 261 (6) ◽  
pp. G1005-G1011 ◽  
Author(s):  
J. R. Del Castillo ◽  
V. M. Rajendran ◽  
H. J. Binder
Keyword(s):  
Atpase Activity ◽  
Parietal Cell ◽  
Colonic Mucosa ◽  
Apical Membrane ◽  
Distal Colon ◽  
Proximal Colon ◽  
Gastric Parietal Cell ◽  
Fold Enrichment ◽  
Rat Distal Colon ◽  
Apical Membranes

This study sought to establish the presence of K(+)-activated adenosinetriphosphatase (ATPase) activity in the colonic mucosa of the rat distal colon. K(+)-activated ATPase activity was present in apical membranes but not in basolateral membranes. K(+)-activated ATPase activity in apical membranes represented an approximate 10-fold enrichment compared with that in the homogenate. Na(+)-K(+)-activated ATPase activity was also present in homogenate but was enriched less than fourfold in apical membranes. K(+)-activated ATPase activity in apical membranes had both ouabain-sensitive and ouabain-insensitive components. In contrast, Na(+)-K(+)-activated ATPase activity was completely inhibited by ouabain. Similar half-maximal concentrations for K+ and pH activation curves were found for both ouabain-sensitive and ouabain-insensitive fractions. In addition to K+, the ouabain-sensitive fraction of K(+)-activated ATPase activity was stimulated by Rb+, NH+4, and Cs+, whereas the ouabain-insensitive fraction was activated only by Rb+. K(+)-activated ATPase activity was significantly inhibited by vanadate but not by N-ethylmaleimide or omeprazole. In the proximal colon, in contrast to the distal colon, active K+ absorption is not present, and K(+)-activated ATPase is approximately 20% of that in the distal colon. These studies demonstrate that K(+)-activated ATPase is present in apical membranes of rat distal colon and permit the speculation that this enzyme represents a unique and distinct ATPase (compared with either Na(+)-K(+)-ATPase or gastric parietal cell K(+)-ATPase) and is likely linked closely to the active K+ absorptive process present in this epithelium.

Colonic H-K-ATPase α- and β-subunits express ouabain-insensitive H-K-ATPase

2000 ◽  
Vol 278 (1) ◽  
pp. C182-C189 ◽  
Author(s):  
Pitchai Sangan ◽  
Sundararajah Thevananther ◽  
Sheela Sangan ◽  
Vazhaikkurichi M. Rajendran ◽  
Henry J. Binder
Keyword(s):  
Atpase Activity ◽  
Plasma Membranes ◽  
Expression System ◽  
Distal Colon ◽  
Rat Colon ◽  
Β Subunit ◽  
Α Subunit ◽  
Hek 293 ◽  
Transfected Cells ◽  
Rat Distal Colon

Active K absorption in the rat distal colon is energized by an apical H-K-ATPase, a member of the gene family of P-type ATPases. The H-K-ATPase α-subunit (HKcα) has been cloned and characterized (together with the β-subunit of either Na-K-ATPase or gastric H-K-ATPase) in Xenopus oocytes as ouabain-sensitive86Rb uptake. In contrast, HKcα, when expressed in Sf9 cells without a β-subunit, yielded evidence of ouabain-insensitive H-K-ATPase. Because a β-subunit (HKcβ) has recently been cloned from rat colon, this present study was initiated to determine whether H-K-ATPase and its sensitivity to ouabain are expressed when these two subunits (HKcα and HKcβ) are transfected into a mammalian cell expression system. Transfection of HEK-293 cells with HKcα and HKcβ cDNAs resulted in the expression of HKcα and HKcβ proteins and their delivery to plasma membranes. H-K-ATPase activity was identified in crude plasma membranes prepared from transfected cells and was 1) saturable as a function of increasing K concentration with a K m for K of 0.63 mM; 2) inhibited by orthovanadate; and 3) insensitive to both ouabain and Sch-28080. In parallel transfection studies with HKcα and Na-K-ATPase β1 cDNAs and with HKcα cDNA alone, there was expression of ouabain-insensitive H-K-ATPase activity that was 60% and 21% of that in HKcα/HKcβ cDNA transfected cells, respectively. Ouabain-insensitive 86Rb uptake was also identified in cells transfected with HKcα and HKcβ cDNAs. These studies establish that HKcα cDNA with HKcβ cDNA express ouabain-insensitive H-K-ATPase similar to that identified in rat distal colon.

Regulation of intracellular pH in crypt cells from rabbit distal colon

1994 ◽  
Vol 267 (3) ◽  
pp. G409-G415 ◽  
Author(s):  
S. L. Abrahamse ◽  
A. Vis ◽  
R. J. Bindels ◽  
C. H. van Os
Keyword(s):  
Intracellular Ph ◽  
Distal Colon ◽  
Buffering Capacity ◽  
Colonic Crypt ◽  
Bafilomycin A1 ◽  
Acid Load ◽  
Intracellular Buffering Capacity ◽  
Crypt Cells ◽  
Exchange Activity ◽  
In Cells

H+ secretory mechanisms and intrinsic intracellular buffering capacity were studied in crypt cells from rabbit distal colon. To this end crypts of Lieberkuhn were isolated by microdissection, and intracellular pH (pHi) was measured using digital imaging fluorescence microscopy and the pH-sensitive fluorescent dye 2',7'-bis(2-carboxyethyl)- 5(6)-carboxyfluorescein. In the absence of HCO(3-)-CO2 and presence of Na+, resting pHi was 7.51 +/- 0.04 (n = 237/23, cells/crypts). However, 6 min after superfusion with a solution containing zero Na+, 1 x 10(5) M Sch-28080 and 5 x 10(-8) M bafilomycin A1, pHi in cells at the bottom of the crypts was significantly reduced, whereas pHi in cells at the top of the crypts remained unchanged. The intrinsic buffering capacity of cells from the middle to the top portion of crypts was significantly higher in the pHi range 7.2-7.6 than of cells at the bottom of the crypt. H+ secretion after an NH(4+)-NH3 pulse amounted to 245 +/- 53 microM/s (n = 73/7) at pHi 7.1 and was largely Na+ dependent and ethylisopropylamiloride sensitive. The Na(+)-independent recovery of pHi after an acid load was insensitive to Sch-28080 and bafilomycin A1. In conclusion, pHi in colonic crypt cells is regulated through Na+/H+ exchange activity in the absence of HCO3-. In addition, intracellular buffering capacity varied with the position along the crypt axis, whereas Na+/H+ exchange activity and pHi did not.

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

2001 ◽  
Vol 280 (3) ◽  
pp. G400-G405 ◽  
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.

Nongastric H-K-ATPase in rodent prostate: lobe-specific expression and apical localization

2002 ◽  
Vol 282 (4) ◽  
pp. C907-C916 ◽  
Author(s):  
Nikolay B. Pestov ◽  
Tatyana V. Korneenko ◽  
Gail Adams ◽  
Manoranjani Tillekeratne ◽  
Mikhail I. Shakhparonov ◽  
...  
Keyword(s):  
Lateral Lobe ◽  
Distal Colon ◽  
Pcr Analysis ◽  
Protein Abundance ◽  
Ventral Lobe ◽  
Rt Pcr ◽  
Specific Expression ◽  
Α Subunit ◽  
Apical Membranes ◽  
Coagulating Gland

The molecular basis of active ion transport in secretory glands such as the prostate is not well characterized. Rat nongastric H-K-ATPase is expressed at high levels in distal colon surface cell apical membranes and thus is referred to as “colonic.” Here we show that the ATPase is expressed in rodent prostate complex in a lobe-specific manner. RT-PCR and Western blot analyses indicate that rat nongastric H-K-ATPase α-subunit (αng) mRNA and protein are present in coagulating gland (anterior prostate) and lateral and dorsal prostate and absent from ventral lobe, whereas Na-K-ATPase α-subunit is present in all lobes. RT-PCR analysis shows that Na-K-ATPase α4 and α3 and gastric H-K-ATPase α-subunit are not present in significant amounts in all prostate lobes. Relatively low levels of Na-K-ATPase α2were found in lateral, dorsal, and anterior lobes. αngprotein expression is anteriodorsolateral: highest in coagulating gland, somewhat lower in dorsal lobe, and even lower in lateral lobe. Na-K-ATPase protein abundance has the reverse order: expression in ventral lobe is higher than in coagulating gland. αngprotein abundance is higher in coagulating gland than distal colon membranes. Immunohistochemistry shows that in rat and mouse coagulating gland epithelium αng protein has an apical polarization and Na-K-ATPase α1 is localized in basolateral membranes. The presence of nongastric H-K-ATPase in rodent prostate apical membranes may indicate its involvement in potassium concentration regulation in secretions of these glands.

Stimulation of Cl permeability in colonic crypts of Lieberkuhn measured with a fluorescent indicator

1993 ◽  
Vol 265 (3) ◽  
pp. G423-G431 ◽  
Author(s):  
D. R. Halm ◽  
K. L. Kirk ◽  
K. C. Sathiakumar
Keyword(s):  
Epithelial Cell ◽  
Distal Colon ◽  
Cell Type ◽  
Fluorescent Indicator ◽  
Epithelial Cell Type ◽  
Colonic Crypts ◽  
Pg E2 ◽  
Crypt Cells ◽  
Stimulation Of ◽  
Cl Permeability

Crypts of Lieberkuhn were isolated from rabbit distal colon and the halide-sensitive dye 6-methoxy-N-[3-sulfopropyl]quinolinium was used to monitor changes in cell Cl by fluorescence microscopy. Distal colon from rabbits actively secretes Cl and K when stimulated with prostaglandin (PG) E2 but secretes only K in response to epinephrine. The secretagogues PGE2 and epinephrine each produced transient decreases of the apparent cell Cl concentration in about one-half of the crypt cells. Permeability to Cl was assessed by brief substitutions with gluconate or Br in the bath. After stimulation of secretion by PGE2 or epinephrine, Cl efflux and Br influx were increased but only in the cells that exhibited the decrease in cell Cl at the onset of stimulation. Although Cl efflux during gluconate substitution was stimulated similarly with either PGE2 or epinephrine, epinephrine stimulation led to a lower apparent Cl concentration after 2 min of gluconate substitution. Together these results support the concept that a particular epithelial cell type in the crypts responds to secretagogues and that the Cl permeability pathways differ between the secretory states induced by PGE2 and epinephrine.

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

1994 ◽  
Vol 266 (1) ◽  
pp. G71-G82 ◽  
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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