Ion transport characteristics of the murine trachea and caecum

1992 ◽  
Vol 82 (6) ◽  
pp. 667-672 ◽  
Author(s):  
S. N. Smith ◽  
E. W. F. W. Alton ◽  
D. M. Geddes
Keyword(s):  
Cystic Fibrosis ◽  
Ion Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Open Circuit ◽  
Potential Difference ◽  
Cystic Fibrosis Gene ◽  
Tissue Type ◽  
Ussing Chambers

1. The basic defect in cystic fibrosis relates to abnormalities of ion transport in affected tissues, such as the respiratory and gastrointestinal tracts. The identification of the cystic fibrosis gene has enabled studies on the production of a cystic fibrosis transgenic mouse to be undertaken. Knowledge of normal ion transport will be necessary for the validation of any such animal model. We have therefore characterized selected responses of the murine trachea and caecum mounted in ‘mini’ Ussing chambers under open-circuit conditions. 2. Basal values for the trachea were: potential difference, 1.1 mV (sem 0.2; n=18); equivalent short-circuit current, 20.4 μA/cm2 (3.6); conductance, 18.2 mS/cm2 (1.7). Corresponding values for the caecum were: potential difference, 0.7 mV (0.1; n=18); equivalent short-circuit current, 11.0 μA/cm2 (1.6); conductance, 14.5 mS/cm2 (1.4). 3. Amiloride (10 μmol/l) produced a significant (P < 0.001) fall in potential difference of 43.0% (5.7) in the trachea, but had no significant effect in the caecum. 4. Subsequently, one of three protocols was used to assess the capacity of either tissue for chloride secretion. Addition of a combination of forskolin (1 μmol/l) and zardaverine (10 μmol/l) produced rises in the potential difference of 873% (509) in the trachea and 399% (202) in the caecum. Both A23187 (10 μmol/l) and phorbol dibutyrate (10 nmol/l) increased tracheal potential difference by 350% (182) and 147% (47), respectively. Neither had a significant effect in the caecum. 5. Subsequent addition of bumetanide caused a fall in the stimulated potential difference of between 39.8% and 71.7%, depending on secretagogue and tissue type. 6. When a homozygous transgenic cystic fibrosis mouse becomes available, these responses should allow such an animal to be distinguished from normal or heterozygous mice.

Regional differences in the response to platelet-activating factor in rabbit colon

1992 ◽  
Vol 82 (6) ◽  
pp. 673-680 ◽  
Author(s):  
S. P. L. Travis ◽  
D. P. Jewell
Keyword(s):  
Ion Transport ◽  
Regional Differences ◽  
Chloride Transport ◽  
Short Circuit ◽  
Platelet Activating Factor ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Chloride Secretion ◽  
Anion Secretion ◽  
Ussing Chambers

1. Platelet-activating factor is an inflammatory mediator related to eicosanoids which is known to stimulate anion secretion in the distal colon. Since there are regional differences in ion transport within the colon, the influence of platelet-activating factors on ion transport and epithelial permeability has been studied in rabbit caecum and distal colon mounted in Ussing chambers. 2. The effect of platelet-activating factor (1–50 nmol/l) on net electrogenic ion transport was to stimulate a biphasic increase in short-circuit current in the distal colon but not in the caecum. The platelet-activating factor-induced rise in short-circuit current was shown by ion replacement and pharmacological inhibitor studies to be consistent with chloride and bicarbonate secretion in the early phase, but with chloride secretion alone in the later phase. The effect on ion transport was specific and reversible and was enhanced by 0.25% BSA. 3. Colonic permeability, assessed by transmucosal resistance and mannitol flux, was increased by platelet-activating factor in both the distal colon and the caecum. This was consistent with an effect on platelet-activating factor on the paracellular pathway, because resistance decreased even when transcellular chloride transport was inhibited by frusemide or ion replacement. A specific platelet-activating factor antagonist (U66985) inhibited the effects of platelet-activating factor in both the distal colon and the caecum. 4. The results show that platelet-activating factor stimulates anion secretion only in the distal colon, but increases permeability in both the caecum and the distal colon.

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.

Pharmacological modulation of ion transport across wild-type and ΔF508 CFTR-expressing human bronchial epithelia

2000 ◽  
Vol 279 (2) ◽  
pp. C461-C479 ◽  
Author(s):  
Daniel C. Devor ◽  
Robert J. Bridges ◽  
Joseph M. Pilewski
Keyword(s):  
Cystic Fibrosis ◽  
Ion Transport ◽  
Short Circuit ◽  
Primary Cultures ◽  
Short Circuit Current ◽  
Bronchial Epithelium ◽  
Disulfonic Acid ◽  
Wild Type ◽  
Pharmacological Agents ◽  
Transport Defect

Forskolin, UTP, 1-ethyl-2-benzimidazolinone (1-EBIO), NS004, 8-methoxypsoralen (Methoxsalen; 8-MOP), and genistein were evaluated for their effects on ion transport across primary cultures of human bronchial epithelium (HBE) expressing wild-type (wt HBE) and ΔF508 (ΔF-HBE) cystic fibrosis transmembrane conductance regulator. In wt HBE, the baseline short-circuit current ( I sc) averaged 27.0 ± 0.6 μA/cm2 ( n = 350). Amiloride reduced this I sc by 13.5 ± 0.5 μA/cm2 ( n = 317). In ΔF-HBE, baseline I sc was 33.8 ± 1.2 μA/cm2 ( n = 200), and amiloride reduced this by 29.6 ± 1.5 μA/cm2 ( n = 116), demonstrating the characteristic hyperabsorption of Na+ associated with cystic fibrosis (CF). In wt HBE, subsequent to amiloride, forskolin induced a sustained, bumetanide-sensitive I sc(Δ I sc = 8.4 ± 0.8 μA/cm2; n = 119). Addition of acetazolamide, 5-( N-ethyl- N-isopropyl)-amiloride, and serosal 4,4′-dinitrostilben-2,2′-disulfonic acid further reduced I sc, suggesting forskolin also stimulates HCO3 − secretion. This was confirmed by ion substitution studies. The forskolin-induced I scwas inhibited by 293B, Ba2+, clofilium, and quinine, whereas charybdotoxin was without effect. In ΔF-HBE the forskolin I sc response was reduced to 1.2 ± 0.3 μA/cm2 ( n = 30). In wt HBE, mucosal UTP induced a transient increase in I sc (Δ I sc = 15.5 ± 1.1 μA/cm2; n = 44) followed by a sustained plateau, whereas in ΔF-HBE the increase in I sc was reduced to 5.8 ± 0.7 μA/cm2 ( n = 13). In wt HBE, 1-EBIO, NS004, 8-MOP, and genistein increased I sc by 11.6 ± 0.9 ( n = 20), 10.8 ± 1.7 ( n = 18), 10.0 ± 1.6 ( n = 5), and 7.9 ± 0.8 μA/cm2( n = 17), respectively. In ΔF-HBE, 1-EBIO, NS004, and 8-MOP failed to stimulate Cl− secretion. However, addition of NS004 subsequent to forskolin induced a sustained Cl−secretory response (2.1 ± 0.3 μA/cm2, n = 21). In ΔF-HBE, genistein alone stimulated Cl− secretion (2.5 ± 0.5 μA/cm2, n = 11). After incubation of ΔF-HBE at 26°C for 24 h, the responses to 1-EBIO, NS004, and genistein were all potentiated. 1-EBIO and genistein increased Na+ absorption across ΔF-HBE, whereas NS004 and 8-MOP had no effect. Finally, Ca2+-, but not cAMP-mediated agonists, stimulated K+ secretion across both wt HBE and ΔF-HBE in a glibenclamide-dependent fashion. Our results demonstrate that pharmacological agents directed at both basolateral K+ and apical Cl− conductances directly modulate Cl−secretion across HBE, indicating they may be useful in ameliorating the ion transport defect associated with CF.

A primary cation transport by a V-type ATPase of low specificity

1996 ◽  
Vol 199 (6) ◽  
pp. 1327-1334 ◽  
Author(s):  
J Küppers ◽  
I Bunse
Keyword(s):  
Ion Transport ◽  
Proton Transport ◽  
Short Circuit ◽  
Membrane Conductance ◽  
Short Circuit Current ◽  
Potential Difference ◽  
Lepidopteran Larvae ◽  
The Family ◽  
K Transport

The enzyme involved in outward K+ transport in insect epithelia belongs to the family of V-ATPases. Evidence has been reported relating the generation of the K+ gradient to a primary electrogenic proton transport via a distinct electrophoretic nH+/K+ antiport. The subject of this paper is the transport of K+ at a thread hair sensillum of the cockroach in situ. We recorded changes in the voltage and resistance of the ion-transporting membrane and of shifts in pH caused by inhibition of energy metabolism and by putative inhibitors of a proton/cation exchanger. The results are supplemented by previous determinations of the K+ activities in the same preparation. 1. In cockroach hair sensilla, the ion transport generates a membrane voltage of 105 mV. We found that the transport rendered the positive output compartment alkaline with respect to the cytoplasm by 1.0 pH unit compared with the pH at equilibrium distribution, and we infer that proton transport cannot be the process that energizes the generation of the K+ gradient. 2. The ion transport created an electrochemical potential difference for protons, DeltaetaH, of approximately 4.5 kJ mol-1, while the potential difference for K+, DeltaetaK, amounted to approximately 11 kJ mol-1. Both potential differences are directed to the cytosol. It follows from DeltaetaK/DeltaetaH that an antiport would have to be electrophoretic to drive K+ by DeltaetaH and it should, therefore, contribute to the membrane conductance. Amiloride and harmaline did not significantly change the pH in the adjacent spaces and did not affect the voltage or the resistance of the transporting membrane. Previous determinations of the impedance have shown that the ATP-independent conductance of this membrane is small, supporting the conclusion that it lacks an electrophoretic antiport. From these results, we deduce that K+ transport in cockroach sensilla is not secondary to a proton transport and an electrochemical proton gradient. The phenomena observed match the performance of a primary, electrogenic, cation-translocating ATPase of the type deduced from analyses of the short-circuit current at the midgut epithelium of lepidopteran larvae. The validity of the H+ transport/antiport hypothesis is discussed.

Aldosterone response in the turtle bladder is associated with an increase in ATP

1983 ◽  
Vol 245 (4) ◽  
pp. F512-F514
Author(s):  
N. Cortas ◽  
E. Abras ◽  
M. Walser
Keyword(s):  
Perchloric Acid ◽  
Sodium Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Potential Difference ◽  
Freshwater Turtles ◽  
Active Sodium ◽  
Active Sodium Transport ◽  
Turtle Bladder

Urinary bladders from freshwater turtles, mounted as sacs, were stripped of their serosa and submucosa. This did not alter conductance. They were maintained in open circuit except for brief observation of short-circuit current (SCC) every 15 min. Potential difference (PD) averaged 68 +/- 14 mV and SCC 485 +/- 100 microA. Acetazolamide 10(-3) M increased SCC by 46 +/- 27 microA. Aldosterone 10(-7) M following acetazolamide resulted in a rise in SCC that began at about 75 min and reached a plateau between 3 and 5 h. SCC rose 127 +/- 15% compared with control bladder halves. ATP measured in perchloric acid extracts 5 h after addition of aldosterone increased by 33% (P less than 0.01) and (ATP)/(ADP) X (Pi) by 81% (P less than 0.01). These results support the view that the stimulatory effects of aldosterone on active sodium transport involve an increase in ATP and (ATP)/(ADP) X (Pi).

scholarly journals Nobiletin Stimulates Chloride Secretion in Human Bronchial Epithelia via a cAMP/PKA-Dependent Pathway

2015 ◽  
Vol 37 (1) ◽  
pp. 306-320 ◽  
Author(s):  
Yuan Hao ◽  
Cindy S.T. Cheung ◽  
Wallace C.Y. Yip ◽  
Wing-hung Ko
Keyword(s):  
Cystic Fibrosis ◽  
Adenylate Cyclase ◽  
Cell Line ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Epithelial Cell Line ◽  
Electrical Measurements ◽  
Cl Secretion ◽  
Bronchial Epithelia

Background/Aims: Nobiletin, a citrus flavonoid isolated from tangerines, alters ion transport functions in intestinal epithelia, and has antagonistic effects on eosinophilic airway inflammation of asthmatic rats. The present study examined the effects of nobiletin on basal short-circuit current (ISC) in a human bronchial epithelial cell line (16HBE14o-), and characterized the signal transduction pathways that allowed nobiletin to regulate electrolyte transport. Methods: The ISC measurement technique was used for transepithelial electrical measurements. Intracellular calcium ([Ca2+]i) and cAMP were also quantified. Results: Nobiletin stimulated a concentration-dependent increase in ISC, which was due to Cl- secretion. The increase in ISC was inhibited by a cystic fibrosis transmembrane conductance regulator inhibitor (CFTRinh-172), but not by 4,4'-diisothiocyano-stilbene-2,2'-disulphonic acid (DIDS), Chromanol 293B, clotrimazole, or TRAM-34. Nobiletin-stimulated ISC was also sensitive to a protein kinase A (PKA) inhibitor, H89, and an adenylate cyclase inhibitor, MDL-12330A. Nobiletin could not stimulate any increase in ISC in a cystic fibrosis (CF) cell line, CFBE41o-, which lacked a functional CFTR. Nobiletin stimulated a real-time increase in cAMP, but not [Ca2+]i. Conclusion: Nobiletin stimulated transepithelial Cl- secretion across human bronchial epithelia. The mechanisms involved activation of adenylate cyclase- and cAMP/PKA-dependent pathways, leading to activation of apical CFTR Cl- channels.

Prostaglandin-induced recovery of barrier function in porcine ileum is triggered by chloride secretion

1999 ◽  
Vol 276 (1) ◽  
pp. G28-G36 ◽  
Author(s):  
Anthony T. Blikslager ◽  
Malcolm C. Roberts ◽  
Robert A. Argenzio
Keyword(s):  
Short Circuit ◽  
Second Messengers ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Ringer Solution ◽  
Signal Recovery ◽  
Osmotic Gradient ◽  
Current Increase ◽  
Ussing Chambers

We have previously shown that PGI2 and PGE2 have a synergistic role in restoring electrical transepithelial resistance ( R) in ischemia-injured porcine ileum via the second messengers Ca2+ and cAMP. Because Ca2+ and cAMP stimulate Cl− secretion, we assessed the role of PG-induced Cl−secretion in recovery of R. Mucosa from porcine ileum subjected to ischemia for 45 min was mounted in Ussing chambers and bathed in indomethacin and Ringer solution. Addition of PGs stimulated a twofold increase in R, which was preceded by elevations in short-circuit current (increase of 25 μA/cm2). The PG-induced effect on R was partially inhibited with bumetanide, an inhibitor of Cl− secretion. The remaining elevations in R were similar in magnitude to those induced in ischemic tissues by amiloride, an inhibitor of Na+ absorption. Treatment with 10−4 M 8-bromo-cGMP or 300 mosM mucosal urea resulted in elevations in R similar to those attained with PG treatment. PGs signal recovery of Rvia induction of Cl−secretion and inhibition of Na+absorption, possibly by establishing a transmucosal osmotic gradient.

Ion transport across cat and ferret tracheal epithelia

1986 ◽  
Vol 61 (3) ◽  
pp. 1065-1070 ◽  
Author(s):  
R. J. Corrales ◽  
D. L. Coleman ◽  
D. B. Jacoby ◽  
G. D. Leikauf ◽  
H. L. Hahn ◽  
...  
Keyword(s):  
Ion Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Free Medium ◽  
Mucin Secretion ◽  
Ussing Chambers ◽  
Cl Secretion ◽  
Mucosal Side

Sheets of trachea from ferret and cat were mounted in Ussing chambers and continuously short circuited. Under resting conditions, in both the cat and ferret there was little or no Cl secretion, and Na absorption accounted for most of the short-circuit current (Isc). Ouabain (10(-4) M, serosal bath) reduced Isc to zero in 30–60 min. This decline was matched by a decrease in net Na absorption. Amiloride (10(-4) M, luminal bath) caused a significant decrease in Isc and conductance (G) in both species. Bumetanide (10(-4) M, serosal bath) had negligible effects on Isc and G. In both species, isoproterenol increased Isc by stimulating Cl secretion. Methacholine induced equal amounts of Na and Cl secretion, with little change in Isc. In the cat, prostaglandins E2 and F2 alpha and bradykinin increased Isc, responses which were abolished in Cl-free medium. In open-circuited cat tissues, Na flux from the serosal to mucosal side was measured simultaneously with the secretion of nondialyzable 35S. Prostaglandins E1, E2, and F2 alpha, histamine, bradykinin, methacholine and isoproterenol all increased both Na and 35S-mucin secretion.

Neuromodulation of ion transport in porcine distal colon: NPY reduces secretory actions of leukotrienes

1995 ◽  
Vol 269 (2) ◽  
pp. R426-R431 ◽  
Author(s):  
T. R. Traynor ◽  
D. R. Brown ◽  
S. M. O'Grady
Keyword(s):  
Ion Transport ◽  
Colonic Mucosa ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Effective Concentration ◽  
Leukotriene C4 ◽  
Ussing Chambers ◽  
Cl Secretion ◽  
Half Maximal Effective Concentration

Electrical transmural stimulation (ETS) was used to examine the neuroregulation of electrolyte transport in the porcine distal colon. ETS of the colonic mucosa-submucosa mounted in Ussing chambers produced rapid and transient increases in short-circuit current (Isc) that were inhibited 36% by serosal bumetanide, suggesting that a portion of the response may be attributed to Cl secretion. ETS actions were dependent upon stimulus intensity and frequency and were inhibited by tetrodotoxin and omega-conotoxin. Prazosin and pyrilamine had no effect on the mucosal responses to ETS, whereas atropine reduced the responses by 32%. Neuropeptide Y (NPY) also reduced the mucosal responses to ETS up to 60% (half-maximal effective concentration = 17 nM). In addition, the effects of leukotriene C4, previously shown to stimulate Cl secretion via a neuronal pathway, were also inhibited by NPY. These results indicate that cholinergic submucosal neurons play a role in the regulation of epithelial ion transport and that NPY acts as an inhibitory neuromodulator, particularly on leukotriene-sensitive neurons in the porcine distal colon.

Intestinal ion transport in rats with spontaneous arterial hypertension

1988 ◽  
Vol 75 (2) ◽  
pp. 127-133 ◽  
Author(s):  
Ralf Lübcke ◽  
Gilbert O. Barbezat
Keyword(s):  
Ion Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Membrane Resistance ◽  
Chloride Secretion ◽  
Sodium Absorption ◽  
Spontaneously Hypertensive ◽  
Wistar Kyoto ◽  
Intestinal Ion Transport

1. Ion balance, intestinal ion transport in vivo with luminal Ringer, and direct voltage clamping in vivo with luminal Ringer and sodium-free choline-Ringer were studied in young (40 days old) and adult (120 days old) spontaneously hypertensive rats (SHR) and age-matched normotensive controls (Wistar–Kyoto rats, WKY). 2. Faecal sodium output was significantly higher in SHR compared with WKY in both young (+ 67%) and adult (+ 43%) rats. 3. Small-intestinal sodium absorption was equal in young SHR and WKY, but significantly greater net sodium absorption was found in the ileum of adult SHR. In contrast, net sodium absorption was reduced from the colon of both young and adult SHR. 4. In adult SHR, the colonic transepithelial short-circuit current (Isc) and the transepithelial potential difference (PD) were significantly higher, whereas the transepithelial membrane resistance (Rm) was significantly lower than in WKY. There was an identical drop in Isc in both strains when luminal sodium was replaced by choline. These data cannot be explained by increased electrogenic cation (sodium) absorption in the SHR, but would favour chloride secretion. 5. It is suggested that in SHR membrane electrolyte transport abnormalities may also be present in the epithelial cells of the small and large intestine, as have been demonstrated already in blood cells by several investigators. The SHR may become an interesting experimental animal model for the study of generalized ion transport disorders.

Sign in / Sign up

Export Citation Format

Share Document