353: Electrolyte transport properties assay revealed less carbachol-stimulated short-circuit current in cultured human small airway epithelia

While pathological and clinical data suggest that small airways are involved in early cystic fibrosis (CF) lung disease development, little is known about how the lack of cystic fibrosis transmembrane conductance regulator (CFTR) function contributes to disease pathogenesis in these small airways. Large and small airway epithelia are exposed to different airflow velocities, temperatures, humidity, and CO2 concentrations. The cellular composition of these two regions is different, and small airways lack submucosal glands. To better understand the ion transport properties and impacts of lack of CFTR function on host defense function in small airways, we adapted a novel protocol to isolate small airway epithelial cells from CF and non-CF pigs and established an organotypic culture model. Compared with non-CF large airways, non-CF small airway epithelia cultures had higher Cl− and bicarbonate (HCO3−) short-circuit currents and higher airway surface liquid (ASL) pH under 5% CO2 conditions. CF small airway epithelia were characterized by minimal Cl− and HCO3− transport and decreased ASL pH, and had impaired bacterial killing compared with non-CF small airways. In addition, CF small airway epithelia had a higher ASL viscosity than non-CF small airways. Thus, the activity of CFTR is higher in the small airways, where it plays a role in alkalinization of ASL, enhancement of antimicrobial activity, and lowering of mucus viscosity. These data provide insight to explain why the small airways are a susceptible site for the bacterial colonization.

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Response of Amphiuma small intestine to theophylline: effect on bicarbonate transport.

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1979.236.6.e775 ◽

1979 ◽

Vol 236 (6) ◽

pp. E775

Author(s):

P J Gunter-Smith ◽

J F White

Keyword(s):

Small Intestine ◽

Transport Properties ◽

Short Circuit ◽

Short Circuit Current ◽

Ion Flux ◽

Electrolyte Transport ◽

Bicarbonate Transport ◽

Na Transport ◽

Transepithelial Potential ◽

Tissue Resistance

The electrolyte transport properties of isolated proximal segments of Amphiuma small intestine and their response to theophylline were observed under various conditions. In the absence of theophylline the intestine generates a transepithelial potential (psi ms) serosa negative to mucosa when Cl- and HCO3- are present in the bath. Replacement of Cl- or HCO3- reduced the magnitude and usually reversed the sign of psi ms. Acetazolamide (10(-4) M) nearly abolished the serosa negative psi ms. Theophylline (10 mM) drove psi ms serosa positive, the magnitude depending on the bath Na+ and HCO3- concentrations. Simultaneously it increased the short-circuit current (Isc) and tissue resistance (Rt). The increase in Isc was not due to increase net Na+ transport in Cl-free buffer and was attributed to a residual ion flux. Acetazolamide reduced the Isc, Rt, and the net residual flux observed in theophylline-treated intestine. The magnitude of the acetazolamine effect on Isc was proportional to the Na+ and HCO3- concentrations of the bath. The results suggest that in the absence of theophylline, HCO3-, and Cl- transport are related. Furthermore, acetazolamide inhibits the movement of an ion, possibly HCO3-, secreted in response to theophylline.

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Active electrolyte transport in mammalian buccal mucosa

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1988.255.3.g286 ◽

1988 ◽

Vol 255 (3) ◽

pp. G286-G291 ◽

Cited By ~ 3

Author(s):

R. C. Orlando ◽

N. A. Tobey ◽

V. J. Schreiner ◽

R. D. Readling

Keyword(s):

Buccal Mucosa ◽

Short Circuit ◽

Basolateral Membrane ◽

Electrical Potential ◽

Short Circuit Current ◽

Electrolyte Transport ◽

Electrical Potential Difference ◽

Ussing Chambers ◽

Net Fluxes

The transmural electrical potential difference (PD) was measured in vivo across the buccal mucosa of humans and experimental animals. Mean PD was -31 +/- 2 mV in humans, -34 +/- 2 mV in dogs, -39 +/- 2 mV in rabbits, and -18 +/- 1 mV in hamsters. The mechanisms responsible for this PD were explored in Ussing chambers using dog buccal mucosa. After equilibration, mean PD was -16 +/- 2 mV, short-circuit current (Isc) was 15 +/- 1 microA/cm2, and resistance was 1,090 +/- 100 omega.cm2, the latter indicating an electrically "tight" tissue. Fluxes of [14C]mannitol, a marker of paracellular permeability, varied directly with tissue conductance. The net fluxes of 22Na and 36Cl were +0.21 +/- 0.05 and -0.04 +/- 0.02 mueq/h.cm2, respectively, but only the Na+ flux differed significantly from zero. Isc was reduced by luminal amiloride, serosal ouabain, or by reducing luminal Na+ below 20 mM. This indicated that the Isc was determined primarily by active Na+ absorption and that Na+ traverses the apical membrane at least partly through amiloride-sensitive channels and exits across the basolateral membrane through Na+-K+-ATPase activity. We conclude that buccal mucosa is capable of active electrolyte transport and that this capacity contributes to generation of the buccal PD in vivo.

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Effects of galanin on short circuit current and electrolyte transport in rabbit ileum

Peptides ◽

10.1016/0196-9781(94)90120-1 ◽

1994 ◽

Vol 15 (8) ◽

pp. 1431-1436 ◽

Cited By ~ 11

Author(s):

Fadia R. Homaidan ◽

Shao Hua Tang ◽

Mark Donowitz ◽

Geoffrey W.G. Sharp

Keyword(s):

Short Circuit ◽

Short Circuit Current ◽

Electrolyte Transport ◽

Rabbit Ileum

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Alterations in capsaicin-evoked electrolyte transport during the evolution of guinea pig TNBS ileitis

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00037.2001 ◽

2002 ◽

Vol 282 (6) ◽

pp. G972-G980 ◽

Cited By ~ 14

Author(s):

Paula Miceli ◽

Gerald P. Morris ◽

Wallace K. MacNaughton ◽

Stephen Vanner

Keyword(s):

Substance P ◽

Guinea Pig ◽

Short Circuit ◽

Short Circuit Current ◽

Electrolyte Transport ◽

Secretory Function ◽

Trinitrobenzenesulfonic Acid ◽

Ussing Chambers ◽

Circulating Cytokines

The efferent secretomotor activity of capsaicin-sensitive nerves was monitored during the evolution of 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced ileitis in the guinea pig by recording changes in short-circuit current (Δ I sc) in response to capsaicin, substance P (SP), and carbachol. Submucosal-mucosal preparations mounted in standard Ussing chambers were studied at time 0, at 8 h, and 1, 3, 5, 7, 14, and 30 days following the intraluminal instillation of TNBS or saline. Maximal Δ I scresponses to capsaicin were dramatically attenuated (54%) by 24 h. By day 7, SP- and TTX-insensitive carbachol-stimulated Δ I sc were also significantly reduced. Similar attenuation in capsaicin and carbachol responses was observed in jejunal tissue 20 cm proximal to the inflamed site at day 7. These studies demonstrate that efferent secretomotor function of capsaicin-sensitive nerves is maintained early in TNBS ileitis but significantly reduced by 24 h. By day 7, defects in enterocyte secretory function at inflamed and noninflamed sites also occurred, an effect that may be mediated by circulating cytokines.

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Corticosteroid alteration of active electrolyte transport in rat distal colon

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1983.245.5.g668 ◽

1983 ◽

Vol 245 (5) ◽

pp. G668-G675 ◽

Cited By ~ 8

Author(s):

E. S. Foster ◽

T. W. Zimmerman ◽

J. P. Hayslett ◽

H. J. Binder

Keyword(s):

Colonic Mucosa ◽

Short Circuit ◽

Short Circuit Current ◽

Distal Colon ◽

Transport Processes ◽

Electrolyte Transport ◽

Sodium Absorption ◽

Rat Distal Colon ◽

Potassium Absorption ◽

Potassium Secretion

To determine the effect of corticosteroids on active transport processes, unidirectional fluxes of 22Na, 36Cl, and 42K were measured under short-circuit conditions across isolated stripped distal colonic mucosa of the rat in control, secondary hyperaldosterone, and dexamethasone-treated animals. In controls net sodium and chloride fluxes (JNanet and JClnet) and short-circuit current (Isc) were 6.6 +/- 2.2, 7.6 +/- 1.6, and 1.3 +/- 0.2 mu eq X h-1 X cm-2, respectively. Although aldosterone increased Isc to 7.3 +/- 0.5 mu eq X h-1 X cm-2, JNanet (6.9 +/- 0.7 mu eq X h-1 X cm-2) was not altered and JClnet was reduced to 0 compared with controls. Dexamethasone also stimulated Isc but did not inhibit JClnet. In Cl-free Ringer both aldosterone and dexamethasone produced significant and equal increases in JNanet and Isc. Theophylline abolished JNanet in control animals but not in the aldosterone group. Aldosterone reversed net potassium absorption (0.58 +/- 0.11 mu eq X h-1 X cm-2) to net potassium secretion (-0.94 +/- 0.08 mu eq X h-1 X cm-2). Dexamethasone reduced net potassium movement to 0 (-0.04 +/- 0.12 mu eq X h-1 X cm-2). These studies demonstrate that 1) corticosteroids stimulate electrogenic sodium absorption and 2) aldosterone, but not dexamethasone, inhibits neutral NaCl absorption and stimulates active potassium secretion. The effects of mineralocorticoids and glucocorticoids on electrolyte transport are not identical and may be mediated by separate and distinct mechanisms.

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Suggestion of a role for calmodulin and phosphorylation in regulation of rabbit ileal electrolyte transport: effects of promethazine

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1986.251.5.g710 ◽

1986 ◽

Vol 251 (5) ◽

pp. G710-G717

Author(s):

M. E. Cohen ◽

G. W. Sharp ◽

M. Donowitz

Keyword(s):

Protein Phosphorylation ◽

Light Chain ◽

Myosin Light Chain ◽

Short Circuit ◽

Short Circuit Current ◽

Electrolyte Transport ◽

Dependent Manner ◽

Low Concentrations ◽

Microvillus Membrane ◽

Membrane Phosphorylation

Suggestion of a role for protein phosphorylation in the regulation of intestinal active NaCl transport was found by studying the effects of low concentrations of promethazine on Ca2+-calmodulin (CaM)-dependent protein phosphorylation of ileal microvillus membranes and on active ileal electrolyte transport. Ca2+-CaM increased the phosphorylation of six microvillus peptides (Mr 137,000, 116,000, 77,000, 58,000, 53,000, and 50,000) in a concentration-dependent manner. Promethazine inhibited the Ca2+-CaM-induced increases in each of these phosphorylations. The effect of promethazine was concentration dependent, with concentrations of 5–12 microM (mean 8 microM) causing 50% inhibition. Promethazine also caused a concentration-dependent increase in net Cl absorption and decrease in the ileal short-circuit current, with 9 microM promethazine causing a change in short-circuit current 50% of maximum. The promethazine effect on microvillus membrane phosphorylation was specific, since neither cAMP- and cGMP-induced phosphorylation in the microvillus membrane nor the stimulation by Ca2+-CaM of myosin light chain kinase phosphorylation of myosin light chain were affected by promethazine. The similar, and unusual sensitivity to low concentrations of promethazine on ileal microvillus membrane phosphorylation increased by Ca2+-CaM and on ileal electrolyte transport is consistent with Ca2+-CaM-dependent microvillus membrane phosphorylation being involved in the regulation of active electrolyte transport in ileal absorptive cells.

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Modulated Photocurrent Spectroscopy Study of the Electronic Transport Properties of Working Organic Photovoltaics: Degradation Analysis

Materials ◽

10.3390/ma13112660 ◽

2020 ◽

Vol 13 (11) ◽

pp. 2660

Author(s):

Emi Nakatsuka ◽

Yo Kumoda ◽

Kiyohito Mori ◽

Takashi Kobayashi ◽

Takashi Nagase ◽

...

Keyword(s):

Transport Properties ◽

Organic Photovoltaics ◽

Electronic Transport ◽

Short Circuit ◽

Photovoltaic Performance ◽

Acid Methyl Ester ◽

Short Circuit Current ◽

Electronic Transport Properties ◽

Photocurrent Spectroscopy ◽

Donor And Acceptor

Electronic transport measurement using modulated photocurrent (MPC) spectroscopy is demonstrated herein in working organic photovoltaics (OPVs) before and after AM1.5G irradiation. OPVs with bulk heterojunction (BHJ) using prototypical donor and acceptor materials, poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1–2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl] = hieno [3–4-b]thiophenediyl]] (PTB7) and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM), were fabricated. The OPVs had inverted structures (BHJs are formed on transparent conductive oxide substrates). The photovoltaic performance of PTB7:PC71BM OPVs was characterized and the best power conversion efficiency was obtained at PTB7 content of 40 wt%. Electron and hole mobility were determined with MPC spectroscopy in PTB7:PC71BM OPVs and were well balanced at PTB7 content of 40 wt%. Degradation of the photovoltaic performance of PTB7:PC71BM OPVs with PTB7 content of 40 wt% caused by AM1.5G irradiation was studied. MPC spectroscopy showed that the well-balanced mobility was not affected by AM1.5G irradiation. The degradation of OPVs was not due to changes in the electronic transport properties, but mainly to the reduced short circuit current (Jsc) and fill factor (FF). The origin of this reduction is discussed.

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Water and electrolyte transport by rabbit esophagus

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1975.229.2.438 ◽

1975 ◽

Vol 229 (2) ◽

pp. 438-443 ◽

Cited By ~ 32

Author(s):

DW Powell ◽

SM Morris ◽

DD Boyd

Keyword(s):

Sodium Transport ◽

Short Circuit ◽

Short Circuit Current ◽

Electrolyte Transport ◽

Potential Difference ◽

Sodium Absorption ◽

Bathing Solution ◽

Electrical Potential Difference

The nature of the transmural electrical potential difference and the characteristics of water and electrolyte transport by rabbit esophagus were determined with in vivo and in vitro studies. The potential difference of the perfused esophagus in vivo was -28 +/- 3 mV (lumen negative). In vitro the potential difference was -17.9 +/- 0.6 mV, the short-circuit current 12.9 +/- 0.6 muA/cm2, and the resistance 1,466 +/- 43 ohm-cm2. Net mucosal-to-serosal sodium transport from Ringer solution in the short-circuited esophagus in vitro accounted for 77% of the simultaneously measured short-circuit current and net serosal-to-mucosal chloride transport for 14%. Studies with bicarbonate-free, chloride-free, and bicarbonate-chloride-free solutions suggested that the net serosal-to mucosal transport of these two anions accounts for the short-circuit current not due to sodium absorption. The potential difference and short-circuit current were saturating functions of bathing solution sodium concentration and were inhibited by serosal ouabain and by amiloride. Thus active mucosal-to-serosal sodium transport is the major determinant of the potential difference and short-circuit current in this epithelium.

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Activation of an apical Cl- conductance by Ca2+ ionophores in cystic fibrosis airway epithelia

AJP Cell Physiology ◽

10.1152/ajpcell.1989.256.2.c226 ◽

1989 ◽

Vol 256 (2) ◽

pp. C226-C233 ◽

Cited By ~ 97

Author(s):

N. J. Willumsen ◽

R. C. Boucher

Keyword(s):

Cystic Fibrosis ◽

Apical Membrane ◽

Short Circuit ◽

Short Circuit Current ◽

Airway Epithelia ◽

Cl Secretion ◽

Human Nasal Epithelium ◽

Collagen Membranes ◽

Cl Conductance ◽

Dependent Mechanism

Cystic fibrosis (CF) airway epithelia express a defect in adenosine 3',5'-cyclic monophosphate (cAMP)-dependent regulation of apical membrane Cl- channels. Recent patch-clamp studies have raised the possibility that Ca2+ -dependent mechanisms for the activation of Cl- secretion may be preserved in CF airway epithelia. To determine 1) whether intact normal (N1) and CF airway epithelia exhibit a Ca2+ -dependent mechanism for activation of Cl- secretion and 2) whether Ca2+ -dependent mechanism for activation of Cl- secretion and 2) whether Ca2+ -dependent mechanisms initiate Cl- secretion via activation of an apical membrane Cl- conductance (GCl-), nasal epithelia from N1 and CF subjects were cultured on collagen membranes, and responses to isoproterenol or Ca2- ionophores [A23187 10(-6) M; ionomycin (10(-5)M)] were measured with transepithelial and intracellular techniques. Isoproterenol induced activation of an apical membrane GCl- in N1 cultures but was ineffective in CF. In contrast, in both N1 and CF amiloride-pretreated cultures, A23187 induced an increase in the equivalent short-circuit current that was associated with an activation of an apical membrane Gc1- and was bumetanide inhibitable. A23187 addition during superfusion of the lumen with a low Cl- (3 mM) solution reduced intracellular Cl- activity of CF cells. A Ca2+ ionophore of different selectivity properties, ionomycin, was also an effective Cl- secretagogue in both N1 and CF cultures. We conclude that 1) the A23187 induced Cl- secretion via activation of an apical GCl- in N1 human nasal epithelium, and 2) in contrast to an isoproterenol-dependent path, a Ca2+ -dependent path for GCl- activation is preserved in CF epithelia.

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