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.

Regulation of intracellular pH in J774 murine macrophage cells: H+ extrusion processes

1995 ◽  
Vol 268 (1) ◽  
pp. C210-C217 ◽  
Author(s):  
L. C. McKinney ◽  
A. Moran
Keyword(s):  
Intracellular Ph ◽  
Initial Rate ◽  
Adherent Cells ◽  
Murine Macrophage ◽  
Bafilomycin A1 ◽  
Macrophage Cell ◽  
Recovery From Acidification ◽  
J774 Cells ◽  
Acid Load ◽  
Rate Of Recovery

Mechanisms of intracellular pH (pHi) regulation were characterized in the murine macrophage cell line J774.1, using 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein to measure pHi. Under nominally HCO3(-)-free conditions, resting pHi of nonadherent J774.1 cells was 7.53 +/- 0.02 (n = 86), and of adherent cells was 7.59 +/- 0.02 (n = 97). In the presence of HCO3-/CO2, pHi values were reduced to 7.41 +/- 0.02 (n = 12) and 7.40 +/- 0.01 (n = 28), respectively. Amiloride, an inhibitor of Na+/H+ exchange, did not affect resting pHi. Inhibitors of a vacuolar type H(+)-ATPase [bafilomycin A1, N-ethylmaleimide (NEM), 7-chloro-4-nitrobenz-2-oxa-1,3-diazide (NBD), and p-chloromercuriphenylsulfonic acid (pCMBS)] reduced pHi by at least 0.2 pH units. Inhibitors of other classes of H(+)-ATPases (oligomycin, azide, vanadate, and ouabain) were without effect. Inhibition of H+ efflux, measured by the change in extracellular pH of a weakly buffered cell suspension, followed the same pharmacological profile, indicating that the reduction of pHi was due to inhibition of H+ extrusion. Mechanisms of recovery from an imposed intracellular acid load were also investigated. In NaCl-Hanks' solution, pHi recovered exponentially to normal within 2 min. The initial rate of recovery was inhibited > 90% by amiloride or by replacement of extracellular Na+ concentration by N-methyl-glucamine. Inhibitors of the vacuolar H(+)-ATPase also inhibited recovery. NEM and NBD nonspecifically inhibited all recovery. Bafilomycin A1 and pCMBS did not inhibit the initial amiloride-sensitive portion of recovery, but they did inhibit a late component of recovery when pHi was above 7.0. We conclude that the Na+/H+ exchanger is primarily responsible for recovery from an acid load but does not regulate resting pHi. Conversely, a vacuolar H(+)-ATPase regulates the resting pHi of J774 cells but contributes little to recovery from acidification.

Intracellular pH regulation in the rabbit cortical collecting duct A-type intercalated cell

1997 ◽  
Vol 273 (3) ◽  
pp. F340-F347 ◽  
Author(s):  
A. E. Milton ◽  
I. D. Weiner
Keyword(s):  
Intracellular Ph ◽  
Ph Regulation ◽  
Collecting Duct ◽  
Cortical Collecting Duct ◽  
Bafilomycin A1 ◽  
Proton Secretion ◽  
Acid Load ◽  
A Cell ◽  
Phi Regulation ◽  
Intracellular Acid

The A cell may possess multiple H+ transporters, including H(+)-adenosinetriphosphatase (H(+)-ATPase) and H(+)-K(+)-ATPase. The current study examines the relative roles of proton transporters in the A cell by observing their contribution to both basal intracellular pH (pHi) regulation and pHi recovery from an intracellular acid load. CCD were studied using in vitro microperfusion, and pHi was measured in the individual A cell using the fluorescent, pH-sensitive dye, 2',7'-bis(carboxyethyl)-5(6)-carboxy-fluorescein (BCECF). Inhibiting H(+)-ATPase with luminal bafilomycin A1 decreased basal pHi, whereas inhibiting apical H(+)-K(+)-ATPase with either luminal Sch-28080 or luminal potassium removal did not. The predominant mechanism of pHi, recovery from an intracellular acid load was peritubular sodium dependent and peritubular ethylisopropylamiloride (EIPA) sensitive, identifying basolateral Na+/H+ exchange activity. In the absence of peritubular sodium, pHi recovery was inhibited by luminal bafilomycin A1 but not by luminal Sch-28080 addition or by luminal potassium removal. However, when Na+/H+ exchange was inhibited with EIPA, both bafilomycin A1 sensitive and potassium dependent, Sch-28080-sensitive components of pHi recovery were present. Quantitatively, the rate of H(+)-ATPase proton secretion was greater than the rate of H(+)-K(+)-ATPase proton secretion. We conclude that basolateral Na+/H+ exchange is the predominant mechanism of A cell pHi recovery from an intracellular acid load. An apical H(+)-ATPase is the primary apical transporter contributing to A cell pHi regulation. An apical H(+)-K(+)-ATPase, while present, plays a more limited role under the conditions tested.

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.

Intracellular pH regulation of human colonic crypt cells

1994 ◽  
Vol 426 (3-4) ◽  
pp. 267-275 ◽  
Author(s):  
B�la Teleky ◽  
Gerhard Hamilton ◽  
Enrico Cosentini ◽  
Georg Bischof ◽  
Martin Riegler ◽  
...  
Keyword(s):  
Intracellular Ph ◽  
Ph Regulation ◽  
Colonic Crypt ◽  
Intracellular Ph Regulation ◽  
Crypt Cells

scholarly journals ATP Dependence of Na+/H+ Exchange

1997 ◽  
Vol 109 (2) ◽  
pp. 117-128 ◽  
Author(s):  
Nicolas Demaurex ◽  
Robert R. Romanek ◽  
John Orlowski ◽  
Sergio Grinstein
Keyword(s):  
Chinese Hamster ◽  
Atp Depletion ◽  
Patch Clamp Technique ◽  
Cytosolic Ph ◽  
Pipette Solution ◽  
Optimal Function ◽  
Lipid Kinases ◽  
Acid Load ◽  
Exchange Activity ◽  
In Cells

We studied the ATP dependence of NHE-1, the ubiquitous isoform of the Na+/H+ antiporter, using the whole-cell configuration of the patch-clamp technique to apply nucleotides intracellularly while measuring cytosolic pH (pHi) by microfluorimetry. Na+/H+ exchange activity was measured as the Na+-driven pHi recovery from an acid load, which was imposed via the patch pipette. In Chinese hamster ovary (CHO) fibroblasts stably transfected with NHE-1, omission of ATP from the pipette solution inhibited Na+/H+ exchange. Conversely, ATP perfusion restored exchange activity in cells that had been metabolically depleted by 2-deoxy-d-glucose and oligomycin. In cells dialyzed in the presence of ATP, no “run-down” was observed even after extended periods, suggesting that the nucleotide is the only diffusible factor required for optimal NHE-1 activity. Half-maximal activation of the antiporter was obtained at ∼5 mM Mg-ATP. Submillimolar concentrations failed to sustain Na+/H+ exchange even when an ATP regenerating system was included in the pipette solution. High ATP concentrations are also known to be required for the optimal function of other cation exchangers. In the case of the Na/Ca2+ exchanger, this requirement has been attributed to an aminophospholipid translocase, or “flippase.” The involvement of this enzyme in Na+/H+ exchange was examined using fluorescent phosphatidylserine, which is actively translocated by the flippase. ATP depletion decreased the transmembrane uptake of NBD-labeled phosphatidylserine (NBD-PS), indicating that the flippase was inhibited. Diamide, an agent reported to block the flippase, was as potent as ATP depletion in reducing NBD-PS uptake. However, diamide had no effect on Na+/H+ exchange, implying that the effect of ATP is not mediated by changes in lipid distribution across the plasma membrane. K-ATP and ATPγS were as efficient as Mg-ATP in sustaining NHE-1 activity, while AMP-PNP and AMP-PCP only partially substituted for ATP. In contrast, GTPγS was ineffective. We conclude that ATP is the only soluble factor necessary for optimal activity of the NHE-1 isoform of the antiporter. Mg2+ does not appear to be essential for the stimulatory effect of ATP. We propose that two mechanisms mediate the activation of the antiporter by ATP: one requires hydrolysis and is likely an energy-dependent event. The second process does not involve hydrolysis of the γ-phosphate, excluding mediation by protein or lipid kinases. We suggest that this effect is due to binding of ATP to an as yet unidentified, nondiffusible effector that activates the antiporter.

scholarly journals Genomic Priming of the Antisecretory Response to Estrogen in Rat Distal Colon throughout the Estrous Cycle

2009 ◽  
Vol 30 (6) ◽  
pp. 751-751
Author(s):  
Fiona O'Mahony ◽  
Rodrigo Alzamora ◽  
Ho-Lam Chung ◽  
Warren Thomas ◽  
Brian J. Harvey
Keyword(s):  
Estrogen Receptor ◽  
Estrous Cycle ◽  
Intestinal Secretion ◽  
Distal Colon ◽  
Estrogen Receptor Α ◽  
Transcriptional Level ◽  
Colonic Crypt ◽  
Estrogen Regulation ◽  
Antisecretory Effect ◽  
Crypt Cells

ABSTRACT The secretion of Cl− across distal colonic crypt cells provides the driving force for the movement of fluid into the luminal space. 17β-Estradiol (E2) produces a rapid and sustained reduction in secretion in females, which is dependent on the novel protein kinase Cδ (PKCδ) isozyme and PKA isoform I targeting of KCNQ1 channels. This sexual dimorphism in the E2 response is associated with a higher expression level of PKCδ in female compared with the male tissue. The present study revealed the antisecretory response is regulated throughout the female reproductive (estrous) cycle and is primed by genomic regulation of the kinases. E2 (1-10 nm) decreased cAMP-dependent secretion in colonic epithelia during the estrous, metestrous, and diestrous stages. A weak inhibition of secretion was demonstrated in the proestrous stage. The expression levels of PKCδ and PKA fluctuated throughout the estrous cycle and correlated with the potency of the antisecretory effect of E2. The expression of PKCδ and PKA were up-regulated by estrogen at a transcriptional level via a PKCδ-MAPK-cAMP response element-binding protein-regulated pathway indicating a genomic priming of the antisecretory response. PKCδ was activated by the membrane-impermeant E2-BSA, and this response was inhibited by the estrogen receptor antagonist ICI 182,780. The 66-kDa estrogen receptor-α isoform was present at the plasma membrane of female colonic crypt cells with a lower abundance found in male colonic crypts. The study demonstrates estrogen regulation of intestinal secretion both at a rapid and transcriptional level, demonstrating an interdependent relationship between both nongenomic and genomic hormone responses.

Characterization of PGE2 receptors in isolated rabbit colonic crypt cells

1995 ◽  
Vol 268 (2) ◽  
pp. G270-G275 ◽  
Author(s):  
F. R. Homaidan ◽  
L. Zhao ◽  
R. Burakoff
Keyword(s):  
Binding Sites ◽  
Dissociation Constants ◽  
Distal Colon ◽  
Scatchard Analysis ◽  
Colonic Crypt ◽  
Effector Cells ◽  
Colonic Crypts ◽  
Specific Receptors ◽  
Crypt Cells

The physiological effects of prostaglandins (PG) are mediated through their interactions with specific receptors on effector cells. In this study the properties of PGE2 receptors in the rabbit distal colon were examined. We report the presence of specific, saturable, and high-affinity binding sites of PGE2 of the EP2 subtype in isolated colonic crypts. Scatchard analysis revealed the presence of two binding sites with dissociation constants of 0.3 and 10.8 nM and corresponding maximum number of receptors of 15 and 134 fmol/10(6) cells. From competition experiments in the presence of guanosine 5'-O-(3-thiotriphosphate), PGE2 binding was decreased, suggesting that the receptor is coupled to a G protein. No PGE2 binding sites were detected in surface cells. Levels of adenosine 3',5'-cyclic monophosphate (cAMP) were measured in isolated epithelial cells after being exposed to different concentrations of PGE2. cAMP levels were significantly increased only in the crypt cells when exposed to PGE2. These data provide the first demonstration for the existence of PGE2 receptors on colonic crypt cells, which when activated lead to increased levels of cAMP.

Intracellular pH regulation in isolated myocytes from adult rat heart in HCO-3-containing and HCO-3-free media

1993 ◽  
Vol 84 (2) ◽  
pp. 133-139 ◽  
Author(s):  
L. L. Ng ◽  
J. E. Davies ◽  
P. Quinn
Keyword(s):  
Intracellular Ph ◽  
Ventricular Myocytes ◽  
Ph Regulation ◽  
Specific Inhibitor ◽  
Buffering Capacity ◽  
Intracellular Acidosis ◽  
Rat Ventricular Myocytes ◽  
Adult Rat ◽  
Acid Load ◽  
Free Media

1. Using microfluorimetry, intracellular pH, buffering capacity and intracellular pH recovery from intracellular acidosis were determined in isolated adult rat ventricular myocytes, in buffers with and without HCO-3. 2. In nominally HCO-3-free media, the intracellular pH was higher than in HCO-3-containing media. Buffering capacity at resting intracellular pH and at a pH of about 6.3 was also lower in HCO-3-free media. 3. In HCO-3-free media, recovery from an acid load after an NH4C1 prepulse was almost completely inhibited by the Na+/H+ antiport activity specific inhibitor ethylisopropyl amiloride. However, in the presence of HCO-3, H+ efflux rate was enhanced, and ethylisopropyl amiloride led to only partial inhibition of H+ efflux. Complete inhibition was achieved only with further addition of the anion-transport inhibitor 4,4′-di-isothiocyanatostilbene-2,2′-disulphonate. 4. Thus, in adult rat ventricular myocytes, recovery from intracellular acidosis in the absence of HCO-3 was almost wholly due to Na+/H+ antiport activity. In the more physiological situation with HCO-3 present, a third of the recovery from an intracellular acid load was attributed to an additional external Na+-dependent di-isothiocyanatostilbene-disulphonate-sensitive H+ efflux.

scholarly journals Genomic Priming of the Antisecretory Response to Estrogen in Rat Distal Colon throughout the Estrous Cycle

2009 ◽  
Vol 94 (11) ◽  
pp. 4627-4628
Author(s):  
Fiona O'Mahony ◽  
Rodrigo Alzamora ◽  
Ho-Lam Chung ◽  
Warren Thomas ◽  
Brian J. Harvey
Keyword(s):  
Estrogen Receptor ◽  
Estrous Cycle ◽  
Intestinal Secretion ◽  
Distal Colon ◽  
Estrogen Receptor Α ◽  
Transcriptional Level ◽  
Colonic Crypt ◽  
Estrogen Regulation ◽  
Antisecretory Effect ◽  
Crypt Cells

Abstract The secretion of Cl− across distal colonic crypt cells provides the driving force for the movement of fluid into the luminal space. 17β-Estradiol (E2) produces a rapid and sustained reduction in secretion in females, which is dependent on the novel protein kinase Cδ (PKCδ) isozyme and PKA isoform I targeting of KCNQ1 channels. This sexual dimorphism in the E2 response is associated with a higher expression level of PKCδ in female compared with the male tissue. The present study revealed the antisecretory response is regulated throughout the female reproductive (estrous) cycle and is primed by genomic regulation of the kinases. E2 (1–10 nm) decreased cAMP-dependent secretion in colonic epithelia during the estrous, metestrous, and diestrous stages. A weak inhibition of secretion was demonstrated in the proestrous stage. The expression levels of PKCδ and PKA fluctuated throughout the estrous cycle and correlated with the potency of the antisecretory effect of E2. The expression of PKCδ and PKA were up-regulated by estrogen at a transcriptional level via a PKCδ-MAPK-cAMP response element-binding protein-regulated pathway indicating a genomic priming of the antisecretory response. PKCδ was activated by the membrane-impermeant E2-BSA, and this response was inhibited by the estrogen receptor antagonist ICI 182,780. The 66-kDa estrogen receptor-α isoform was present at the plasma membrane of female colonic crypt cells with a lower abundance found in male colonic crypts. The study demonstrates estrogen regulation of intestinal secretion both at a rapid and transcriptional level, demonstrating an interdependent relationship between both nongenomic and genomic hormone responses.

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