Absorption of Fluid by the Midgut of Rhodnius

1981 ◽  
Vol 94 (1) ◽  
pp. 301-316 ◽  
Author(s):  
J. FARMER ◽  
S.H. P. MADDRELL ◽  
J. H. SPRING
Keyword(s):  
Cyclic Amp ◽  
Active Transport ◽  
Electrical Resistance ◽  
Fluid Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Ions ◽  
Potential Difference ◽  
Sodium Ions ◽  
Transport Fluid

1. Isolated midguts of 5th-instar Rhodnius prolixus will transport fluid from the lumen that is close to iso-osmotic with the luminal contents. 2. The transported fluid contains sodium and chloride ions as its major constituents. 3. Fluid transport can be attributed to active transport of sodium ions from the lumen. The haemolymph side of the epithelium, towards which transport is directed, is at a potential positive with respect to the lumen; this potential difference is greatly increased if the lumen contains only impermeant anions, and the rate of fluid transport is strongly dependent on the concentration of sodium ions in the luminal fluid. 4. The rate of fluid transport is increased approximately six times by treatment with 5-hydroxytryptamine (2×10−7M) or cyclic AMP (2x−3M). The transepithelial potential is increased by such treatment but the major effects are on the short-circuit current, which increases by about five times, and on the electrical resistance of the epithelium, which falls to about a quarter of its earlier value. Note:

Ion transport across rumen and omasum epithelium

1971 ◽  
Vol 262 (842) ◽  
pp. 301-305 ◽  
Keyword(s):  
Active Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Ions ◽  
Rumen Epithelium ◽  
Sodium Flux ◽  
Sodium System ◽  
Chloride Pump ◽  
Net Flux ◽  
Cattle And Sheep

The interior of the rumen in cattle and sheep is normally maintained at a potential of about — 40 mV relative to the blood. This potential depends primarily on the occurrence of an active transport of sodium from rumen to blood, since the potential, short-circuit current and the net sodium flux are simultaneously abolished by anoxia, ouabain and removal of sodium from the bathing solutions. There is an appreciable net flux of potassium from blood to rumen. There is also a substantial active transport of chloride in the same direction as sodium and it can be reduced by treatment with acetazolamide without affecting the potential or the sodium system. Nevertheless, sodium transport is reduced by the removal of chloride ions. Omasum epithelium is similar to rumen epithelium. However, the chloride pump appears to work in both directions in this tissue. Short-circuited omasum epithelium can also transport magnesium from omasum to blood.

Fluid transport across cultured bovine corneal endothelial cell monolayers

1992 ◽  
Vol 262 (1) ◽  
pp. C98-C103 ◽  
Author(s):  
P. Narula ◽  
M. Xu ◽  
K. Y. Kuang ◽  
R. Akiyama ◽  
J. Fischbarg
Keyword(s):  
Endothelial Cell ◽  
Electrical Resistance ◽  
Corneal Endothelium ◽  
Fluid Transport ◽  
Corneal Endothelial Cell ◽  
Potential Difference ◽  
Cell Monolayers ◽  
Transport Fluid ◽  
Bovine Corneal Endothelial Cell

The mammalian corneal endothelium is known to transport fluid from the stromal compartment to the aqueous humor, thereby maintaining corneal transparency. Corneal endothelial cells have been cultured for some years now, but whether they preserve their in vivo ability to actively transport fluid is not known. We have now grown bovine corneal endothelial cell monolayers (BCECM) on permeable substrates (Transwell) and report that, just like their counterparts in vivo, these cultured cells pump fluid from the basal to the apical compartment and display measurable electrical resistance and potential difference across the monolayer. BCECM were grown on collagen-treated permeable supports using Dulbecco's modified Eagle's medium (DMEM)/20% fetal bovine serum with antibiotics. Cells grew to confluence in 5-7 days and displayed polygonal shape. Only cells from passages 1-3 were utilized. Inserts were fitted directly into Lucite chambers specially built. The rate of fluid pumping by BCECM was 3.96 +/- 0.49 (SE) microliter.h-1.cm-2 (n = 13) and could be measured continuously for several hours; fluid pumping was inhibited by 0.2 mM amiloride. The specific electrical resistance of the monolayers was 180 +/- 22 omega.cm2 (n = 11). A mean electrical potential difference of 63.8 +/- 3.7 microV (n = 15, range 40-100 microV, apical side negative) was recorded across the monolayers in DMEM. The availability of the commercial inserts makes this procedure practical; as a consequence, the rate of fluid transport by cultured corneal endothelium has been quantitated for the first time. This method can now be extended to other cultured layers.(ABSTRACT TRUNCATED AT 250 WORDS)

Fluid absorption related to ion transport in human airway epithelial spheroids

1999 ◽  
Vol 277 (6) ◽  
pp. L1096-L1103 ◽  
Author(s):  
Peter Steen Pedersen ◽  
Niels-Henrik Holstein-Rathlou ◽  
Per Leganger Larsen ◽  
Klaus Qvortrup ◽  
Ole Frederiksen
Keyword(s):  
Cell Membrane ◽  
Fluid Transport ◽  
Short Circuit ◽  
Ciliated Cell ◽  
Short Circuit Current ◽  
Repeated Measurements ◽  
Potential Difference ◽  
Airway Epithelial ◽  
Fluid Absorption ◽  
Osmotic Water

Airway epithelium explants from cystic fibrosis (CF) patients and non-CF subjects formed monolayered spheres, with the apical ciliated cell membrane facing the bath and the basolateral cell membrane pointing toward a fluid-filled lumen. With the use of two microelectrodes, transepithelial potential difference and changes in potential difference in response to passage of current pulses were recorded, and epithelial resistance and the equivalent short-circuit current were calculated. Non-CF control potential difference and short-circuit current values were significantly lower than the CF values, and amiloride inhibited both values. Fluid transport rates were calculated from repeated measurements of spheroid diameters. The results showed that 1) non-CF and CF spheroids absorbed fluid at identical rates (4.4 μl ⋅ cm−2 ⋅ h−1), 2) amiloride inhibited fluid absorption to a lower residual level in non-CF than in CF spheroids, 3) Cl−-channel inhibitors increased fluid absorption in amiloride-treated non-CF spheroids to a level equal to that of amiloride-treated CF spheroids, 4) hydrochlorothiazide reduced the amiloride-insensitive fluid absorption in both non-CF and CF spheroids, and 5) osmotic water permeabilities were equal in non-CF and CF spheroids (∼27 × 10−7cm ⋅ s−1 ⋅ atm−1).

scholarly journals The Origin of the Short-Circuit Current in the Isolated Skin of the South American Frog Leptodactylus ocellatus

1963 ◽  
Vol 47 (2) ◽  
pp. 393-402 ◽  
Author(s):  
José A. Zadunaisky ◽  
Oscar A. Candia ◽  
Dante J. Chiarandini
Keyword(s):  
Copper Ions ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Ions ◽  
Potential Difference ◽  
South American ◽  
The South ◽  
Net Flux ◽  
American Frog ◽  
Short Circuit Condition

In isolated skins of Leptodactylus ocellatus the short-circuit current is smaller than the sodium net flux and this difference disappears when the skins are bathed in solutions in which the chloride ions have been replaced by sulfate or methylsulfate ions. There is a net movement of chloride ions from outside to inside of the skins in the short-circuit condition with chloride Ringer's solutions bathing the skins. The addition of ouabain to the inside solution markedly reduced not only sodium net flux but also the chloride net influx found. Copper ions added to the outside solutions produced a rise in short-circuit current, as well as the known increase in potential difference. In sodium-free Ringer's (sodium replaced by choline) the orientation of the potential difference across the skins was reversed, the inside being negative instead of positive. The results are interpreted as direct or indirect indications of the presence of a net transfer of chloride ions from outside to inside of these frog skins.

scholarly journals Ion Transport in Isolated Rabbit Ileum

1964 ◽  
Vol 47 (3) ◽  
pp. 567-584 ◽  
Author(s):  
Stanley G. Schultz ◽  
Ralph Zalusky
Keyword(s):  
Active Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Passive Diffusion ◽  
Potential Difference ◽  
Rabbit Ileum ◽  
Ionic Flux ◽  
Low Concentrations ◽  
Influence Of Solvent

The transmural potential difference, short-circuit current, and Na fluxes have been investigated in an in vitro preparation of isolated rabbit ileum. When the tissue is perfused with a physiological buffer, the serosal surface is electrically positive with respect to the mucosal surface and the initial potential difference in the presence of glucose averages 9 mv. Unidirectional and net Na fluxes have been determined under a variety of conditions, and in each instance, most if not all of the simultaneously measured short-circuit current could be attributed to the active transport of Na from mucosa to serosa. Active Na transport is dependent upon the presence of intact aerobic metabolic pathways and is inhibited by low concentrations of ouabain in the serosal medium. A method is described for determining whether a unidirectional ionic flux is the result of passive diffusion alone, in the presence of active transport of that ion in the opposite direction. Using this method we have demonstrated that the serosa-to-mucosa flux of Na may be attributed to passive diffusion with no evidence for the presence of carrier-mediated exchange diffusion or the influence of solvent-drag.

scholarly journals Effect of platelet-activating factor on the electrophysiology of the human Fallopian tube: early mediation of embryo-maternal dialogue?

Reproduction ◽  
2002 ◽  
pp. 523-529 ◽  
Author(s):  
SJ Downing ◽  
SD Maguiness ◽  
JI Tay ◽  
A Watson ◽  
HJ Leese
Keyword(s):  
Epithelial Cells ◽  
Short Circuit ◽  
Ussing Chamber ◽  
Platelet Activating Factor ◽  
Short Circuit Current ◽  
Chloride Ions ◽  
Potential Difference ◽  
Preimplantation Embryos ◽  
Apical Surface ◽  
Dependent Manner

Platelet-activating factor (PAF) is produced by preimplantation embryos and may be involved in the earliest stages of embryo-maternal dialogue. This study explored the potential effects of PAF acting as a signalling agent on human Fallopian tubal epithelial cells grown as a polarized layer in primary culture. The response of the tubal epithelium was assessed in terms of the transepithelial potential difference and short-circuit current (I(scc)), which were recorded using a modified Ussing chamber. Resistance was calculated from the measurements of potential difference and I(scc). PAF (1.9 nmol to 1.9 micromol l(-1)) administered to the apical surface of the cells produced a marked, transient increase in both potential difference and I(scc) in a dose-dependent manner. The mode of action of PAF on the electrophysiological responses of human tubal epithelial cells was investigated. Blockers of Na(+), K(+) and voltage-operated Ca(2+) channels had little effect on PAF action. However, incubation of the epithelial cells in Cl(-)free medium or with a blocker of the Na(+)-K(+)-2Cl(-) cotransporter (Furosemide) reduced the effect of PAF. Blockade of chloride-bicarbonate channels with 4-acetamido-4'-iso-thiocyanostilbene-2.2'-disulphonic acid (SITS) reduced the effect of low doses of PAF only. These results indicate that PAF influences the movement of chloride ions across the tubal epithelial cell and is a candidate molecule for initial embryo-maternal dialogue.

Metabolic Support of Chloride-dependent Short-circuit Current Across Locust Rectum

1982 ◽  
Vol 99 (1) ◽  
pp. 349-362
Author(s):  
M. CHAMBERLIN ◽  
J. E. PHILLIPS
Keyword(s):  
Cyclic Amp ◽  
Short Circuit ◽  
Malpighian Tubule ◽  
Short Circuit Current ◽  
Metabolic Substrates ◽  
Endogenous Substrates ◽  
Tubule Fluid ◽  
Substrate Source ◽  
Stimulation Of

1. Recta of desert locusts were short-circuited and depleted of endogenous substrates by exposing them to saline containing cyclic AMP but no metabolites. Individual substrates were then added to substrate-depleted recta and the change in short-circuit current (Isc) monitored. 2. Proline or glucose (50 mM) caused by far the largest increase in Isc of all substrates tested. Stimulation of the Isc by proline was not dependent upon external sodium, but did require external chloride. 3. Physiological levels of proline also caused a large increase in Isc, while physiological levels of glucose produced a much smaller stimulation. Over 90% of the proline-dependent Isc stimulation can be produced by adding 15 mM proline solely to the lumen side of the tissue. 4. These results are discussed with regard to rectal oxidative metabolism and availability of metabolic substrates in vivo. High levels of proline in Malpighian tubule fluid are probably the major substrate source for rectal Cl−transport. Note:

Calcium secretion in canine tracheal mucosa

1985 ◽  
Vol 59 (4) ◽  
pp. 1191-1195 ◽  
Author(s):  
F. J. Al-Bazzaz ◽  
T. Jayaram
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Potential Difference ◽  
Secretory Process ◽  
Metabolic Inhibitor ◽  
Tracheal Mucosa ◽  
Transepithelial Potential ◽  
Transepithelial Potential Difference

Calcium (Ca) affects many cellular functions of the respiratory tract mucosa and might alter the viscoelastic properties of mucus. To evaluate Ca homeostasis in a respiratory epithelium we investigated transport of Ca by the canine tracheal mucosa. Mucosal tissues were mounted in Ussing-type chambers and bathed with Krebs-Henseleit solution at 37 degrees C. Unidirectional fluxes of 45Ca were determined in tissues that were matched by conductance and short-circuit current (SCC). Under short-circuit conditions there was a significant net Ca secretion of 1.82 +/- 0.36 neq . cm-2 . h-1 (mean +/- SE). Under open-circuit conditions, where the spontaneous transepithelial potential difference could attract Ca toward the lumen, net Ca secretion increased significantly to 4.40 +/- 1.14 compared with 1.54 +/- 1.17 neq . cm-2 . h-1 when the preparation was short-circuited. Addition of a metabolic inhibitor, 2,4-dinitrophenol (2 mM in the mucosal bath), decreased tissue conductance and SCC and slightly decreased the unidirectional movement of Ca from submucosa to lumen. Submucosal epinephrine (10 microM) significantly enhanced Ca secretion by 2.0 +/- 0.63 neq . cm-2 . h-1. Submucosal ouabain (0.1 mM) failed to inhibit Ca secretion. The data suggest that canine tracheal mucosa secretes Ca; this secretory process is augmented by epinephrine or by the presence of a transepithelial potential difference as found under in vivo conditions.

scholarly journals Acid-Base Transport and Control in Locust Hindgut: Artefacts Caused by Short-Circuit Current

1991 ◽  
Vol 155 (1) ◽  
pp. 455-467
Author(s):  
R. BRENT THOMSON ◽  
N. AUDSLEY ◽  
JOHN E. PHILLIPS
Keyword(s):  
Cyclic Amp ◽  
Acid Secretion ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Salt Bridges ◽  
Electrical Parameters ◽  
Acid Base ◽  
Before And After ◽  
And Control ◽  
Stimulation Of

The commonly used method of passing short-circuit current (Isc) across insect epithelia through Ag-AgCl electrodes, without the use of salt bridges, leads to significant OH− production at the cathode (lumen side) when high currents are applied. The alkalization of the lumen previously reported when cyclic AMP was added to short-circuited locust hindgut is a result of this phenomenon rather than cyclic-AMP-mediated stimulation of acid-base transport in the hindgut. When salt bridges are used to pass short-circuit current across locust hindgut, acid secretion (JH) into the lumen equals alkaline movement (JOH) to the haemocoel side, and JH is similar under both open- and short-circuit conditions. JH is similar (1.5 μequiv cm−2 h−1) in recta and ilea. Addition of cyclic AMP inhibits JH across the rectum by 42–66%, but has no effect on the ileum when salt bridges are used. Electrical parameters (Isc, Vt, Rt) reflecting hindgut Cl− transport (JCL) before and after stimulation with cyclic AMP are the same whether or not salt bridges are used. We found no evidence of any coupling between JCl and JH/JOH.

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