Epithelial responses of rabbit tongues and their involvement in taste transduction

The response of rabbit tongue, placed in a modified Ussing chamber, to salts [KCl, NaCl, NH4Cl, tetraethylammonium chloride (TEACl)], sweeteners (D-glucose, sucrose), acid (HCl), and a bitter tastant, quinine, was investigated for the first time. These experiments were conducted to further explore the new paradigm of taste transduction that correlates changes in the electrical behavior of lingual epithelia with neural responses. In addition, the responses of rabbit tongue data were compared with previously published data on dog and frog tongues. When increases in short-circuit current (Isc) for rabbit tongue induced by hyperosmotic concentrations of several salts were compared, the following sequence was found: KCl greater than NH4Cl greater than NaCl greater than TEACl. These results are consistent with previously published integrated chorda tympani responses (ICTR) as well as behavioral studies that showed that rabbits prefer KCl to NaCl with their natural diet. Pharmacological studies using ouabain and amiloride suggest that K and Na are traversing rabbit tongue through different pathways. The maximal stimulation of Isc by D-glucose and sucrose (in 50 mM NaCl) was significantly smaller than those measured for KCl and NaCl. The rabbit tongue was sensitive to HCl at concentrations less than 1 mM in agreement with ICTR measurements.

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Enterotoxigenicity of Mature 45-Kilodalton and Processed 35-Kilodalton Forms of Hemagglutinin Protease Purified from a Cholera Toxin Gene-Negative Vibrio cholerae Non-O1, Non-O139 Strain

Infection and Immunity ◽

10.1128/iai.74.5.2937-2946.2006 ◽

2006 ◽

Vol 74 (5) ◽

pp. 2937-2946 ◽

Cited By ~ 27

Author(s):

A. Ghosh ◽

D. R. Saha ◽

K. M. Hoque ◽

M. Asakuna ◽

S. Yamasaki ◽

...

Keyword(s):

Cholera Toxin ◽

Vibrio Cholerae ◽

Hela Cells ◽

Histopathological Examination ◽

Short Circuit ◽

Ussing Chamber ◽

Short Circuit Current ◽

Toxin Gene ◽

Dependent Manner ◽

A Cell

ABSTRACT Cholera toxin gene-negative Vibrio cholerae non-O1, non-O139 strain PL-21 is the etiologic agent of cholera-like syndrome. Hemagglutinin protease (HAP) is one of the major secretory proteins of PL-21. The mature 45-kDa and processed 35-kDa forms of HAP were purified in the presence and absence of EDTA from culture supernatants of PL-21. Enterotoxigenicities of both forms of HAP were tested in rabbit ileal loop (RIL), Ussing chamber, and tissue culture assays. The 35-kDa HAP showed hemorrhagic fluid response in a dose-dependent manner in the RIL assay. Histopathological examination of 20 μg of purified protease-treated rabbit ileum showed the presence of erythrocytes and neutrophils in the upper part of the villous lamina propria. Treatment with 40 μg of protease resulted in gross damage of the villous epithelium with inflammation, hemorrhage, and necrosis. The 35-kDa form of HAP, when added to the lumenal surface of rat ileum loaded in an Ussing chamber, showed a decrease in the intestinal short-circuit current and a cell rounding effect on HeLa cells. The mature 45-kDa form of HAP showed an increase in intestinal short-circuit current in an Ussing chamber and a cell distending effect on HeLa cells. These results show that HAP may play a role in the pathogenesis of PL-21.

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Basolateral Cl− uptake mechanisms in Xenopus laevis lung epithelium

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00749.2009 ◽

2010 ◽

Vol 299 (1) ◽

pp. R92-R100 ◽

Cited By ~ 3

Author(s):

Jens Berger ◽

Martin Hardt ◽

Wolfgang G. Clauss ◽

Martin Fronius

Keyword(s):

Xenopus Laevis ◽

Ion Transport ◽

Anion Exchanger ◽

Short Circuit ◽

Ussing Chamber ◽

Short Circuit Current ◽

Transport Processes ◽

Lung Epithelium ◽

Active Ion Transport ◽

Uptake Mechanisms

A thin liquid layer covers the lungs of air-breathing vertebrates. Active ion transport processes via the pulmonary epithelial cells regulate the maintenance of this layer. This study focuses on basolateral Cl− uptake mechanisms in native lungs of Xenopus laevis and the involvement of the Na+/K+/2 Cl− cotransporter (NKCC) and HCO3−/Cl− anion exchanger (AE), in particular. Western blot analysis and immunofluorescence staining revealed the expression of the NKCC protein in the Xenopus lung. Ussing chamber experiments demonstrated that the NKCC inhibitors (bumetanide and furosemide) were ineffective at blocking the cotransporter under basal conditions, as well as under pharmacologically stimulated Cl−-secreting conditions (forskolin and chlorzoxazone application). However, functional evidence for the NKCC was detected by generating a transepithelial Cl− gradient. Further, we were interested in the involvement of the HCO3−/Cl− anion exchanger to transepithelial ion transport processes. Basolateral application of DIDS, an inhibitor of the AE, resulted in a significantly decreased the short-circuit current (ISC). The effect of DIDS was diminished by acetazolamide and reduced by increased external HCO3− concentrations. Cl− secretion induced by forskolin was decreased by DIDS, but this effect was abolished in the presence of HCO3−. These experiments indicate that the AE at least partially contributes to Cl− secretion. Taken together, our data show that in Xenopus lung epithelia, the AE, rather than the NKCC, is involved in basolateral Cl− uptake, which contrasts with the common model for Cl− secretion in pulmonary epithelia.

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Enterohemorrhagic E. coli (EHEC)—Secreted Serine Protease EspP Stimulates Electrogenic Ion Transport in Human Colonoid Monolayers

Toxins ◽

10.3390/toxins10090351 ◽

2018 ◽

Vol 10 (9) ◽

pp. 351 ◽

Cited By ~ 3

Author(s):

C. Tse ◽

Julie In ◽

Jianyi Yin ◽

Mark Donowitz ◽

Michele Doucet ◽

...

Keyword(s):

Ion Transport ◽

Serine Protease ◽

Shiga Toxin ◽

Short Circuit ◽

Ussing Chamber ◽

Adult Stem Cell ◽

Short Circuit Current ◽

Watery Diarrhea ◽

E Coli ◽

Electrogenic Ion Transport

One of the characteristic manifestations of Shiga-toxin-producing Escherichia coli (E. coli) infection in humans, including EHEC and Enteroaggregative E. coli O104:H4, is watery diarrhea. However, neither Shiga toxin nor numerous components of the type-3 secretion system have been found to independently elicit fluid secretion. We used the adult stem-cell-derived human colonoid monolayers (HCM) to test whether EHEC-secreted extracellular serine protease P (EspP), a member of the serine protease family broadly expressed by diarrheagenic E. coli can act as an enterotoxin. We applied the Ussing chamber/voltage clamp technique to determine whether EspP stimulates electrogenic ion transport indicated by a change in short-circuit current (Isc). EspP stimulates Isc in HCM. The EspP-stimulated Isc does not require protease activity, is not cystic fibrosis transmembrane conductance regulator (CFTR)-mediated, but is partially Ca2+-dependent. EspP neutralization with a specific antibody reduces its potency in stimulating Isc. Serine Protease A, secreted by Enteroaggregative E. coli, also stimulates Isc in HCM, but this current is CFTR-dependent. In conclusion, EspP stimulates colonic CFTR-independent active ion transport and may be involved in the pathophysiology of EHEC diarrhea. Serine protease toxins from E. coli pathogens appear to serve as enterotoxins, potentially significantly contributing to watery diarrhea.

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Cellular pathways mediating tachykinin-evoked secretomotor responses in guinea pig ileum

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1997.273.5.g1127 ◽

1997 ◽

Vol 273 (5) ◽

pp. G1127-G1134 ◽

Cited By ~ 9

Author(s):

W. MacNaughton ◽

B. Moore ◽

S. Vanner

Keyword(s):

Guinea Pig ◽

Receptor Agonist ◽

Short Circuit ◽

Ussing Chamber ◽

Short Circuit Current ◽

Neurokinin A ◽

Guinea Pig Ileum ◽

Cellular Pathways ◽

20 Nm

This study characterized tachykinin-evoked secretomotor responses in in vitro submucosal and mucosal-submucosal preparations of the guinea pig ileum using combined intracellular and Ussing chamber recording techniques. Superfusion of endogenous tachykinins substance P (SP), neurokinin A (NKA), and neurokinin B depolarized single submucosal neurons and evoked increased short-circuit current ( I sc) responses in Ussing chamber preparations. The NK1-receptor agonist [Sar9,Met(O2)11]SP [50% effective concentration (EC50) = 2 nM] depolarized all submucosal neurons examined. The NK3-receptor agonist senktide (EC50 = 20 nM) depolarized ∼50% of neurons examined, whereas the NK2-receptor agonist [Ala5,β-Ala8]NKA-(4—10) had no effect on membrane potential. [Sar9,Met(O2)11]SP and senktide evoked similar increases in I sc that were tetrodotoxin sensitive (91 and 100%, respectively) and were selectively blocked by the NK1antagonist CP-99,994 and the NK3antagonist SR-142801, respectively. Capsaicin-evoked increases in I sc were significantly inhibited (54%, P < 0.05) by CP-99,994 but not by SR-142801. Neither antagonist inhibited slow excitatory postsynaptic potentials. These findings suggest that tachykinin-evoked secretion in guinea pig ileum is mediated by NK1 and NK3 receptors on submucosal secretomotor neurons and that capsaicin-sensitive nerves release tachykinin(s) that activate the NK1 receptors.

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Optical Losses of Frontal Layers in Superstrate CdS/CdTe Solar Cells Using OPAL2

Coatings ◽

10.3390/coatings11080943 ◽

2021 ◽

Vol 11 (8) ◽

pp. 943

Author(s):

Nowshad Amin ◽

Mohammad Rezaul Karim ◽

Zeid Abdullah ALOthman

Keyword(s):

Solar Cells ◽

Short Circuit ◽

Contact Potential Difference ◽

Short Circuit Current ◽

Optical Losses ◽

Contact Potential ◽

Conducting Oxides ◽

Cdte Solar Cells ◽

First Time ◽

Defect Densities

In this paper, optical losses in CdS/CdTe solar cells are calculated on the basis of the designated reflective index of various frontal layers using an OPAL2 calculator for the first time. Two types of glass (0.1 mm ultra-thin Schott and 1.1 mm standard borosilicate glass) were assumed to be coated by different Transparent-Conducting-Oxides (TCOs) such as SnO2:F, ZnO:Al, and ITO forming frontal layers for CdS/CdTe solar cells in superstrate configuration. Absorption, reflectance, transmittance, and consequently optical bandgap energies are calculated as a function of common thicknesses, used in the literature. The results show that an increase in TCO thickness led to a decrease in optical band gap as well as an enhancement in contact potential difference, which can deteriorate device performance. The optimum thickness of 100 nm for SnO2:F was calculated, while 200 nm for ZnO:Al and ITO show reasonable optical losses caused by reflections at the interfaces’ and the layer’s absorption. It is seen that 80 to 150 nm CdS on ITO might be an effective range to satisfy a high short circuit current and low defect densities at the CdS/CdTe interface. Finally, a minimum 2 μm thickness for the CdTe on the ultra-thin Schott glass coated by optimum layers can result in the highest short circuit current of 28.69 mA/cm2. This work offers a practical equivalent strategy to be applied for any superstrate solar cells containing TCO and CdS frontal layers.

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Use of a modified Ussing chamber to monitor intestinal epithelial and smooth muscle functions

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1991.261.1.g166 ◽

1991 ◽

Vol 261 (1) ◽

pp. G166-G170 ◽

Cited By ~ 1

Author(s):

Y. F. Li ◽

N. W. Weisbrodt ◽

Y. Harari ◽

F. G. Moody

Keyword(s):

Smooth Muscle ◽

Strain Gauge ◽

Short Circuit ◽

Ussing Chamber ◽

Short Circuit Current ◽

Displacement Transducer ◽

Organ Bath ◽

Force Displacement ◽

Dose Dependent ◽

Muscle Functions

A technique that allows the simultaneous monitoring of epithelial and smooth muscle function was developed and used to study rat small intestine in vitro. A Ussing chamber was modified so that a strain gauge force transducer could be sewn to the serosal surface of an intestinal segment clamped in the chamber. The apparatus was used to monitor short-circuit current, potential difference, and resistance across the segment, and contractions of the longitudinal layer of the muscularis externa. Both spontaneous activity and responses to the application of carbachol were recorded. Carbachol applied to the serosal side induced dose-dependent increases in both short-circuit current and contractile force. The median effective doses of the two responses differed, with contractions being more sensitive to the drug. Carbachol applied to the mucosal side induced no changes in either epithelial or contractile activities. The ability of the serosal strain gauge transducer to monitor contractions faithfully was tested in an organ bath in which the gut segment was attached to an external force-displacement transducer. There was a close correlation between the dose-dependent increase in force in response to carbachol measured by the serosal transducer and that measured by the force-displacement transducer (r = 0.988). Thus our technique can be used to study simultaneously epithelial and smooth muscle functions of the intestine.

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Site-1 Protease-Derived Soluble (Pro)Renin Receptor Contributes to Angiotensin II–Induced Hypertension in Mice

Hypertension ◽

10.1161/hypertensionaha.120.15100 ◽

2020 ◽

Author(s):

Ye Feng ◽

Kexin Peng ◽

Renfei Luo ◽

Fei Wang ◽

Tianxin Yang

Keyword(s):

Blood Pressure ◽

Angiotensin Ii ◽

Collecting Duct ◽

Short Circuit ◽

Ussing Chamber ◽

Short Circuit Current ◽

Duct Cell ◽

Ang Ii ◽

Cortical Collecting Duct ◽

Induced Hypertension

Activation of PRR ([pro]renin receptor) contributes to enhancement of intrarenal RAS and renal medullary α-ENaC and thus elevated blood pressure during Ang II (angiotensin II) infusion. The goal of the present study was to test whether such action of PRR was mediated by sPRR (soluble PRR), generated by S1P (site-1 protease), a newly identified PRR cleavage protease. F1 B6129SF1/J mice were infused for 6 days with control or Ang II at 300 ng/kg per day alone or in combination with S1P inhibitor PF-429242 (PF), and blood pressure was monitored by radiotelemetry. S1P inhibition significantly attenuated Ang II–induced hypertension accompanied with suppressed urinary and renal medullary renin levels and expression of renal medullary but not renal cortical α-ENaC expression. The effects of S1P inhibition were all reversed by supplement with histidine-tagged sPRR termed as sPRR-His. Ussing chamber technique was performed to determine amiloride-sensitive short-circuit current, an index of ENaC activity in confluent mouse cortical collecting duct cell line cells exposed for 24 hours to Ang II, Ang II + PF, or Ang II + PF + sPRR-His. Ang II–induced ENaC activity was blocked by PF, which was reversed by sPRR-His. Together, these results support that S1P-derived sPRR mediates Ang II–induced hypertension through enhancement of intrarenal renin level and activation of ENaC.

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Ion transport by neonatal rabbit distal colon

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1986.250.6.g754 ◽

1986 ◽

Vol 250 (6) ◽

pp. G754-G759 ◽

Cited By ~ 4

Author(s):

G. D. Potter ◽

S. M. Burlingame

Keyword(s):

Small Intestine ◽

Short Circuit ◽

Ussing Chamber ◽

Electrical Conductance ◽

Short Circuit Current ◽

Distal Colon ◽

Ion Fluxes ◽

Adult Rabbit ◽

Rabbit Colon ◽

Edge Damage

The neonatal small intestine is characterized by electrical conductance and permeability to ions higher than in the corresponding adult intestine. To investigate whether this property of the neonate is limited to the small intestine, or extends to the colon, a modified Ussing chamber for determination of transmucosal potential difference (PD), short-circuit current (Isc), transepithelial conductance (Gt), and ion fluxes in the neonatal rabbit distal colon was constructed. After care to reduce edge damage, Gt for the neonatal colon was found to be 8.4 +/- 0.3 mS . cm2 and for adult colon in the same chamber, 7.4 +/- 0.5 (P greater than 0.05). Net Na and Cl fluxes under short-circuit conditions were similar to those obtained in adult colon. Unidirectional ion fluxes were also similar to those of the adult. Net Na flux (JNanet) was incompletely inhibited by 10(-4) M of amiloride. Response to replacement of Na, Cl, and HCO3-, respectively, in the bathing solutions was not different from that expected in adult rabbit colon. Thus differences between adult and neonatal rabbit colon were small, and the increased conductance and unidirectional ion fluxes characteristic of the neonatal small intestine were not evident in the neonatal rabbit distal colon.

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Antisecretory effect of prostaglandin D2 in rat colon in vitro: action sites

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1991.260.6.g904 ◽

1991 ◽

Vol 260 (6) ◽

pp. G904-G910 ◽

Cited By ~ 2

Author(s):

K. J. Goerg ◽

C. Diener ◽

M. Diener ◽

W. Rummel

Keyword(s):

Short Circuit ◽

Ussing Chamber ◽

Short Circuit Current ◽

Rat Colon ◽

Prostaglandin D2 ◽

Cyclic Monophosphate ◽

Heat Stable ◽

Antisecretory Effect ◽

Flux Measurements

The effect of prostaglandin D2 (PGD2) on colonic ion transport was studied in the Ussing chamber. PGD2 (10(-6) M) decreased baseline short-circuit current (Isc) in two preparations of rat colon descendens, a mucosa-submucosa preparation with and a mucosa preparation without the submucosal plexus. In both preparations, PGD2 inhibited the neuronally mediated secretory responses to electric field stimulation, the sea anemone toxin ATX II, and different cholinergic agents. Unidirectional flux measurements revealed that PGD2 diminished the secretagogue-induced increase in the serosal-to-mucosal flux of Cl- and thereby inhibited net Cl- secretion. PGD2, however, had no effect on the adenosine 3',5'-cyclic monophosphate-mediated response to forskolin or vasoactive intestinal peptide or on guanosine 3',5'-cyclic monophosphate-mediated secretion induced by the heat-stable enterotoxin of Escherichia coli. The PGD2 also blocked the increase in Isc evoked by two neuronally acting inflammatory mediators, i.e., bradykinin and PGI2 in the mucosa-submucosa preparation, but had no effect on the response to PGE2. Consequently, PGD2 exerts an indirect antisecretory effect caused by an inhibition of enteric secretomotor neurons of both the submucosal and the mucosal plexus.

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Selective effects of bumetanide on chloride transport in bullfrog cornea

AJP Renal Physiology ◽

10.1152/ajprenal.1978.234.4.f297 ◽

1978 ◽

Vol 234 (4) ◽

pp. F297-F301

Author(s):

O. A. Candia ◽

H. F. Schoen

Keyword(s):

Electrical Resistance ◽

Loop Diuretic ◽

Chloride Transport ◽

Short Circuit ◽

Ussing Chamber ◽

Short Circuit Current ◽

Selective Inhibitor ◽

O2 Consumption ◽

Na Transport ◽

Bathing Medium

Frog corneas were mounted in a modified Ussing chamber and short-circuit current (SCC) and unidirectional Cl fluxes were measured. Bumetanide, a loop diuretic, at concentrations as low as 10(-7) M, reduced the SCC 29%. At 10(-5) M, bumetanide reduced the SCC 96% and increased transcorneal electrical resistance 20-51%. The forward Cl flux declined from 0.71 +/- 0.04 to 0.20 +/- 0.03 mueq/h.cm2 (n, 7), while, in separate experiments, the backward Cl flux did not change significantly (from 0.22 +/- 0.03 to 0.23 +/- 0.04; n, 7). When corneas were mounted in Cl-free Ringer and the net Na transport was stimulated with amphotericin B, 10(-5) M bumetanide had no effect on the SCC. In separate experiments the effect of 10(-5) M bumetanide on the O2 consumption was measured in a stirrer bath assembly. Bumetanide decreased the O2 consumption from 352 +/- 14 to 297 +/- 19 microliter/h.cm2 (significantly different from sham-treated controls). This decrease was similar to that obtained with furosemide or when Cl was removed from the bathing medium. We infer from these results that bumetanide is a selective inhibitor of active Cl transport in the bullfrog cornea.

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