scholarly journals Ion Absorption in Atriplex Leaf Tissue III. Site of Metabolic Control of Light-Dependent Chloride Secretion to Epidermal Bladders

1970 ◽  
Vol 23 (1) ◽  
pp. 17 ◽  
Author(s):  
U Lüttge ◽  
CB Osmond
Keyword(s):  
Metabolic Control ◽  
Active Transport ◽  
Chloride Transport ◽  
Leaf Tissue ◽  
Chloride Secretion ◽  
Ion Absorption

The nature and location of the light-stimulated active transport of chloride to the epidermal bladders of A. 8pongio8a leaves was examined. Chloride transport to the bladder vacuole was found to have properties similar to those for light-dependent

Chloride secretion and conductance of teleost opercular membrane: effects of prolactin

1982 ◽  
Vol 242 (3) ◽  
pp. R380-R389 ◽  
Author(s):  
J. K. Foskett ◽  
T. E. Machen ◽  
H. A. Bern
Keyword(s):  
Active Transport ◽  
Short Circuit ◽  
Chloride Secretion ◽  
Alternative Interpretation ◽  
Chloride Cells ◽  
Dependent Manner ◽  
Transport Pathway ◽  
Accurate Analysis ◽  
Equivalent Circuit Analysis ◽  
Fish Yield

Effects of prolactin on transport properties of opercular membranes from seawater-adapted tilapia, Sarotherodon mossambicus, have been examined. These membranes are high conductance (average Gt approximately 4 mS.cm-2) tissues with short-circuit currents (I) equal to net chloride secretion. Despite high Gt, nonlinear current-voltage relationships suggest that opercular membranes cannot be classified as "leaky" tissues. Variability among membranes is reflected in a linear relationship between I and Gt with a slope equal to 26 mV and the zero-current Gt intercept equal to 0.45 mS.cm-2. Prolactin injections decrease I and Gt in a dose-dependent manner. Phosphodiesterase inhibition, without effect on I in untreated fish, often partially reverses these prolactin effects. Gt-I data from prolactin-treated fish yield a slope of 18 mV and a Gt intercept of 0.10 mS.cm-2. The effects of prolactin are discussed in terms of conventional equivalent circuit analysis. Discrepancies between predictions based on this model and the actual data indicate that an alternative interpretation, based on a heterogeneous cell population, is more accurate. Analysis of this circuit suggests that the ratio of paracellular to active transport pathway conductances associated with chloride cells is constant and that differences in Gt and I are due to parallel changes in these conductances. Prolactin may effectively "remove" chloride cells from these membranes as well as inhibit (reversible by elevated cellular cAMP levels) active transport pathway conductance of remaining cells.

Racecadotril directly induces ion absorption under basal condition and inhibits rotavirus chloride secretion in human enterocytes

2008 ◽  
Vol 40 (10) ◽  
pp. A74-A75
Author(s):  
C. Armellino ◽  
V. Buccigrossi ◽  
M. Penza ◽  
I. Bracale ◽  
M. Oliva ◽  
...  
Keyword(s):  
Chloride Secretion ◽  
Ion Absorption

scholarly journals Ion Absorption by Shoot Tissue: Technique and First Findings with Excised Leaf Tissue of Corn

1964 ◽  
Vol 39 (3) ◽  
pp. 338-341 ◽  
Author(s):  
Richard C. Smith ◽  
Emanuel Epstein
Keyword(s):  
Leaf Tissue ◽  
Shoot Tissue ◽  
Ion Absorption

Nitric oxide-mediated regulation of transepithelial sodium and chloride transport in murine nasal epithelium

1999 ◽  
Vol 276 (3) ◽  
pp. L466-L473 ◽  
Author(s):  
Heather L. Elmer ◽  
Kristine G. Brady ◽  
Mitchell L. Drumm ◽  
Thomas J. Kelley
Keyword(s):  
Nitric Oxide ◽  
Chloride Transport ◽  
Chloride Secretion ◽  
Inos Expression ◽  
Potential Difference ◽  
Nasal Epithelium ◽  
Sodium Absorption ◽  
No Production ◽  
Transepithelial Potential ◽  
Transepithelial Potential Difference

Transepithelial ion transport is regulated by a variety of cellular factors. In light of recent evidence that nitric oxide (NO) production is decreased in cystic fibrosis airways, we examined the role of NO in regulating sodium and chloride transport in murine nasal epithelium. Acute intervention with the inducible NO synthase (iNOS)-selective inhibitor S-methylisothiourea resulted in an increase of amiloride-sensitive sodium absorption observed as a hyperpolarization of nasal transepithelial potential difference. Inhibition of iNOS expression with dexamethasone also hyperpolarized transepithelial potential difference, but only a portion of this increase proved to be amiloride sensitive. Chloride secretion was significantly inhibited in C57BL/6J mice by the addition of both S-methylisothiourea and dexamethasone. Mice lacking iNOS expression [NOS2(−/−)] also had a decreased chloride-secretory response compared with control mice. These data suggest that constitutive NO production likely plays some role in the downregulation of sodium absorption and leads to an increase in transepithelial chloride secretion.

Evidence for electroneutral sodium chloride transport in rat proximal convoluted tubule

1986 ◽  
Vol 250 (4) ◽  
pp. F644-F648
Author(s):  
K. J. Howlin ◽  
R. J. Alpern ◽  
C. A. Berry ◽  
F. C. Rector
Keyword(s):  
Sodium Chloride ◽  
Active Transport ◽  
Sodium Transport ◽  
Chloride Transport ◽  
Proximal Convoluted Tubule ◽  
Organic Solutes ◽  
Nacl Transport ◽  
Proximal Tubular ◽  
High Chloride

One- to two-thirds of NaCl absorption in the late proximal convoluted tubule (no luminal organic solutes present) is inhibited by cyanide and thus is dependent on active transport. To examine whether this active transport-dependent NaCl transport is electrogenic or electroneutral, the effect of cyanide on transepithelial potential difference (PD) was measured in the rat proximal convoluted tubule microperfused in vivo. In the presence of an ultrafiltrate-like luminal perfusate containing glucose and alanine, cyanide addition caused the transepithelial PD to change from -0.44 +/- 0.04 to -0.05 +/- 0.03 mV (P less than 0.001). In the presence of a late proximal tubular fluid (high chloride, low bicarbonate, no organics), the transepithelial PD was 1.23 +/- 0.06 mV and was unchanged at 1.19 +/- 0.05 mV after cyanide addition (NS). To eliminate the possibility that an effect of cyanide on a putative acidification-dependent lumen-positive PD was concealing an effect on an electrogenic sodium transport-dependent lumen-negative PD, the above studies were repeated in the presence of acetazolamide. Cyanide did not affect the transepithelial PD (1.17 +/- 0.05 vs. 1.07 +/- 0.06 mV, NS). We conclude that, although cyanide-inhibitable NaCl transport is electrogenic in the presence of luminal organic solutes, it does not generate a transepithelial PD in their absence and therefore is electroneutral.

Developing bronchopulmonary epithelium of the human fetus secretes fluid

1992 ◽  
Vol 262 (3) ◽  
pp. L270-L279 ◽  
Author(s):  
P. B. McCray ◽  
J. D. Bettencourt ◽  
J. Bastacky
Keyword(s):  
Human Fetus ◽  
Chloride Transport ◽  
Fetal Lung ◽  
Fluid Secretion ◽  
Chloride Secretion ◽  
Beta Agonist ◽  
Lung Fluid ◽  
Luminal Area ◽  
Fluid Production ◽  
Human Fetal Lung

We studied human fetal lung tissue in submersion organ culture to determine whether the bronchopulmonary epithelium secretes fluid during development. In this system the acinar tubules continued to grow, secrete fluid, and become progressively dilated. Baseline transepithelial potential differences (psi t) of -0.5 to -11 mV (mean, -3.8 mV, lumen negative, n = 27) were measured with microelectrodes after 3-8 days in culture, suggesting active electrolyte transport. Bumetanide (500 microM), an inhibitor of chloride secretion in other systems, decreased the basal psi t from -5 +/- 1.5 to -3.2 +/- 1.6 (SE) mV (P less than 0.05, n = 6), suggesting that chloride transport contributed to the voltage. Isoproterenol (5 microM) increased the baseline psi t from -5.6 +/- 2.1 to -9.2 +/- 2.5 (SE) mV (P less than 0.05, n = 4). Subsequent addition of bumetanide inhibited the isoproterenol-induced stimulation of the psi t by 20% (P less than 0.05). 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate. (CPT-cAMP, 50 microM) and 3-isobutyl 1-methylxanthine (IBMX, 100 microM) had similar effects, causing an increase in the psi t from -2.2 +/- 0.5 to -8 +/- 1.6 (SE) mV, an effect that was inhibited by the addition of bumetanide (P less than 0.005, n = 6). Both isoproterenol and CPT-cAMP/IBMX produced significant increases in the percentage luminal area of the explants at 12 and 24 h after exposure compared with control. We conclude that 1) the developing bronchopulmonary epithelium (acinar tubules) contributes to lung fluid production in the human fetus, 2) fetal lung fluid secretion is chloride dependent, and 3) chloride secretion and fluid secretion may be stimulated by a beta-agonist and cAMP.

ClC-5: ontogeny of an alternative chloride channel in respiratory epithelia

2002 ◽  
Vol 282 (3) ◽  
pp. L501-L507 ◽  
Author(s):  
Rebecca D. Edmonds ◽  
Ian V. Silva ◽  
William B. Guggino ◽  
Robert B. Butler ◽  
Pamela L. Zeitlin ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Lung Disease ◽  
Chloride Channel ◽  
Chloride Channels ◽  
Chloride Transport ◽  
Premature Death ◽  
Fetal Lung ◽  
Chloride Secretion ◽  
Normal Lung ◽  
Ribonuclease Protection Assay

Chloride transport is critical to many functions of the lung. Molecular defects in the best-known chloride channel, cystic fibrosis transmembrane conductance regulator (CFTR), lead to impaired function of airway defensins, hydration of airway surface fluid, and mucociliary clearance leading to chronic lung disease, and premature death, but do not cause defects in lung development. We examined the expression of one member of the ClC family of volume- and voltage-regulated channels using the ribonuclease protection assay and Western blot analysis in rats. ClC-5 mRNA and protein are most strongly expressed in the fetal lung, and expression is maintained although downregulated postnatally. In addition, using immunocytochemistry, we find that ClC-5 is predominantly expressed along the luminal surface of the airway epithelium, suggesting that ClC-5 may participate in lung chloride secretion. Identifying candidate genes for critical ion transport functions is essential for understanding normal lung morphogenesis and the pathophysiology of several lung diseases. In addition, the manipulation of non-CFTR chloride channels may provide a viable approach for treating cystic fibrosis lung disease.

Chymotrypsin, ileal chloride transport, and neurotransmitters

1984 ◽  
Vol 247 (3) ◽  
pp. G253-G260 ◽  
Author(s):  
K. A. Hubel
Keyword(s):  
Cell Function ◽  
Chloride Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Electrical Field Stimulation ◽  
Chloride Secretion ◽  
Target Cells ◽  
Flux Chamber ◽  
Rabbit Ileum ◽  
Electrical Field

Electrical field stimulation (EFS) depolarizes nerves and causes chloride secretion by mucosa of rabbit ileum mounted in a flux chamber. To test the hypothesis that the transmitter is a peptide, we determined whether the EFS response was prevented by the endopeptidase chymotrypsin (CT). Serosal, but not mucosal, addition of CT (200 micrograms/ml) reduced the short-circuit current (Isc) response to EFS by 90% or more. CT also reduced Cl absorption by decreasing the mucosal-to-serosal flux, but it did not affect net Na absorption. CT prevented the response to vasoactive intestinal polypeptides, but the response returned when CT activity was eliminated. The response to EFS did not return, however, implying that CT damaged cells that released transmitter or epithelial target cells. CT reduced the Isc response to serotonin by 69% and to A23187 by 10% and did not affect the theophylline response. We conclude that 1) the effects of CT on cell function limit its usefulness in identifying peptide neurotransmitters in epithelium, 2) CT irreversibly inhibits ion transport responses to EFS and to serotonin, and 3) CT reduces absorption of Cl probably by affecting a calcium pathway that modifies Cl transport.

scholarly journals Ion Absorption in Atriplex Leaf Tissue I. Absorption by Mesophyll Cells

1968 ◽  
Vol 21 (6) ◽  
pp. 1119 ◽  
Author(s):  
CB Osmond
Keyword(s):  
Diffusion Coefficient ◽  
Leaf Tissue ◽  
External Solution ◽  
Monovalent Cations ◽  
Mesophyll Cells ◽  
Ion Absorption ◽  
Absorption Studies ◽  
Apparent Diffusion ◽  
And Diffusion ◽  
Cut Surface

Leaf tissue cut into disks was unsuitable for quantitative ion-absorption studies because cells in the interior did not equilibrate with the external solution. Ion entry was restricted to the cut surface and diffusion was too slow to permit equilibration of the whole disk (apparent diffusion coefficient for sodium at O� 5�C was 1 X IO-L 3 X 10-7 cm2 sec-I). However, leaf slices 0�5 mm in width permitted rapid access of electrolyte to all cells and were used to study uptake of monovalent cations and oxalate

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