scholarly journals Influence of prostaglandins on unidirectional zinc fluxes across the small intestine of the rat

1988 ◽  
Vol 59 (3) ◽  
pp. 417-428 ◽  
Author(s):  
Moon K. Song ◽  
David B. N. Lee ◽  
Nabeel F. Adham
Keyword(s):  
Short Circuit ◽  
Ussing Chamber ◽  
Short Circuit Current ◽  
Mucosal Cell ◽  
Flux Rate ◽  
Serosal Side ◽  
Uptake Capacity ◽  
Bathing Medium ◽  
Mucosal Side

1. The regulatory role of prostaglandins (PGs) E2 and F2a on the zinc transport rate across the jejunal segments of rats was examined by employing the Ussing chamber technique. The Zn flux rate from mucosa to serosa across jejunal segments (Jms) was 5·24 (SE 1·54) nmol/h per cm2 (n 48) and that from serosa to mucosa (Jsm) was 15·16 (SE 2·38) nmol/h per cm2 (n 48) when both sides of the segment were bathed with Ringer's bicarbonate solution containing 0·5 mM-zinc chloride and 3 mM-L-histidine.2. When 5·0 or 50 μM of either PGE2 or PGF2α were added to the serosal side of the tissue, Jsm generally decreased and Jms generally increased, compared with controls. On the other hand, when PGE2 or PGF2α was added to the mucosal side of the tissue, Jms either did not change or increased while Jsm had a tendency to decrease.3. The Zn uptake capacity of tissue increased significantly when PG was added to the serosal side of the tissuebathing medium, but not when PG was added to the mucosal side. The uptake capacity of mucosal Zn by jejunal segments was approximately twice that of serosal Zn.4. When PG was included in the tissue-bathing medium, the short-circuit current, potential difference and conductance between the mucosa- and serosa-bathing media generally decreased.5. These results suggest that (a) PGs influence Zn flux rate not by chelating Zn and carrying it across the mucosal cell membrane but by interacting with the cytosolic components, (b) it is the serosal PGs which control the Zn flux rate and (c) PGs play a part in triggering a transduction mechanism in the intestinal Zn transport process.

Avian cecum: role of glucose and volatile fatty acids in transepithelial ion transport

1991 ◽  
Vol 260 (5) ◽  
pp. G703-G710 ◽  
Author(s):  
B. R. Grubb
Keyword(s):  
Fatty Acids ◽  
Ion Transport ◽  
Volatile Fatty Acids ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Serosal Side ◽  
Na Transport ◽  
Cl Secretion ◽  
Mucosal Side

In the fowl cecum in vitro, the influence of glucose and the three most prevalent naturally occurring volatile fatty acids (acetate, propionate, butyrate) on short-circuit current (Isc), electrical resistance, and transport of Na and Cl was determined. When glucose, acetate, or butyrate was present, ion transport was characterized by electrogenic Na absorption, greater than 65% of which was amiloride inhibitable, and Cl secretion, which also was electrogenic. Isc could be completely accounted for by net fluxes of Na and Cl. When glucose, acetate, or butyrate (10 mM both sides) was included in the incubation medium, cecal tissue maintained its Isc and a constant rate of net Na absorption and Cl secretion for a 5-h period. When no substrate was present or propionate was included in the medium, a marked fall in Isc and net Na and Cl fluxes was seen. Glucose caused an increase in Isc when added only to the serosal side. As 3-O-methylglucose (not metabolized) was not effective in stimulating Isc of the cecum (serosal or mucosal addition), it appeared that glucose increased Isc by acting as an energy substrate for active Na transport. Acetate and butyrate appeared to be equally effective in stimulating Na transport and Isc when placed on either side of the membrane. When the preparation was supplied with glucose (serosal side) and acetate was added to the mucosal side, no further stimulation of Isc occurred. Thus it appeared that acetate and butyrate were acting as substrates for active Na transport rather than stimulating Na transport by some other mechanism such as a cotransport with Na.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective effects of bumetanide on chloride transport in bullfrog cornea

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.

Ileal mucosal cyclic AMP and Cl secretion: serosal vs. mucosal addition of cholera toxin.

1977 ◽  
Vol 232 (2) ◽  
pp. E210 ◽  
Author(s):  
H E Sheerin ◽  
M Field
Keyword(s):  
Cyclic Amp ◽  
Ion Transport ◽  
Cholera Toxin ◽  
Short Circuit ◽  
Electrical Conductance ◽  
Short Circuit Current ◽  
Serosal Side ◽  
Ileal Mucosa ◽  
Camp Content ◽  
Mucosal Side

Changes in ion transport and cyclic AMP (cAMP) concentration produced by addition of cholera toxin to the serosal side of isolated rabbit ileal mucosa (CTs) were compared to the changes produced by addition to the mucosal side (CTm). CTs increased short-circuit current (SCC) as did CTm but it did so more slowly. CTs, unlike CTm, did not significantly decrease electrical conductance. Inhibition of the SCC response to theophylline, a measure of preexisting secretion, was almost complete 180 min after CTm but was not yet significant 180 min after CTs. Longer (280 min) after CTs, the SCC response to theophylline was reduced by 59%, a significant reduction but less than that caused by CTm. A statistically significant change in net Cl flux could not be demonstrated after CTs, although at 280 min the measured flux was halfway between the fluxes for control and CTm tissues. Cyclic AMP concentrations were determined at 190 min, 10 min after addition of theophylline. CTs, despite little or no effect on ion transport, increased cAMP to the same level as did CTm, and the effect on cAMP of adding toxin to both sides was additive. We conclude that 1) active secretion is probably stimulated by cholera toxin added on the serosal side, although more slowly than after addition to the mucosal side and 2) much of the toxin-stimulated cAMP content of the mucosa is not coupled to secretion.

Abstract P229: Site-1 Protease-derived Soluble (pro) Renin Receptor Mediates Aldosterone-induced Enac Activation In The Collecting Duct

Hypertension ◽  
2020 ◽  
Vol 76 (Suppl_1) ◽  
Author(s):  
Fei Wang ◽  
Renfei Luo ◽  
KEXIN PENG ◽  
Peng Wu ◽  
Xiyang Liu ◽  
...  
Keyword(s):  
Collecting Duct ◽  
Short Circuit ◽  
Ussing Chamber ◽  
Fold Increase ◽  
Short Circuit Current ◽  
Vehicle Group ◽  
Α Subunit ◽  
Collecting Duct Cells

We have previously shown that activation of (pro)renin receptor (PRR) induces epithelial Na + channel (ENaC) activity in cultured collecting duct cells. Here, we examined the role of soluble PRR (sPRR), generated by site-1 protease (S1P), a newly identified PRR cleavage protease, in ENaC regulation, and further tested its relevance to Aldo signaling. In cultured mpkCCD cells, administration of recombinant histidine-tagged sPRR (sPRR-His) at 10 nM for 24 h induced a significant increase in the amiloride-sensitive short-circuit current as assessed using the Ussing chamber technique ( I eq : 7.5 ± 0.7 μA/cm 2 in sPRR group vs. 3.5 ± 0.5 μA/cm 2 in vehicle group, n = 6, p < 0.01) . In primary cultured rat IMCD cells, the same sPRR-His treatment induced a 1.7 fold increase in protein expression of the α-subunit but not β- or γ-subunit of ENaC, in parallel with upregulation of mRNA expression as well as promoter activity of the α-subunit. The upregulation of α-ENaC transcription depended on β-catenin signaling. Consistent results obtained by epithelial volt ohmmeter measurement of equivalent current and Using chamber determination of short-circuit current showed that Aldo-induced ENaC activity was almost completely abolished by PF-429242 (PF), a S1P inhibitor, and the response was restored by supplement of sPRR-His ( I eq : 7.2 ± 0.7 μA/cm 2 in Aldo group vs. 5.0 ± 0.3 μA/cm 2 in Aldo/PF group vs. 6.8 ± 0.3 μA/cm 2 in Aldo/PF/sPRR-His group, n = 5, p < 0.05). Medium sPRR was elevated by Aldo and inhibited by PF. Male C57BL/6 mice were pretreated with PF (30 mg/kg/day) or vehicle via minipump, followed by 3 days of aldosterone (0.2 mg/kg/day via a second minipump). Amiloride-sensitive Na+ current in freshly isolated CCD as measured by using patch clamp lower in Aldo + PF group than in Aldo group. Together, these results support an essential role of S1P-derived sPRR in mediating Aldo-induced ENaC activation.

Emergence of Na+-glucose cotransport in an epithelial secretory cell line sensitive to cholera toxin

1989 ◽  
Vol 256 (2) ◽  
pp. G335-G341 ◽  
Author(s):  
S. K. Nath ◽  
M. Rautureau ◽  
M. Heyman ◽  
H. Reggio ◽  
A. L'Helgoualc'h ◽  
...  
Keyword(s):  
Cholera Toxin ◽  
Cell Line ◽  
Short Circuit ◽  
Tumor Cell Line ◽  
Short Circuit Current ◽  
Serosal Side ◽  
Chloride Flux ◽  
Sodium Flux ◽  
Before And After ◽  
Mucosal Side

Epithelial properties and effects of cholera toxin (CT) and glucose were investigated in human rectal tumor cell line HRT-18. Addition of 10(-3) M dibutyryl adenosine 3',5'-cyclic monophosphate (DbcAMP), 10(-8) M vasoactive intestinal peptide, 10(-5) M epinephrine, and 10(-5) M forskolin to the serosal side and of 3.5 micrograms/ml CT to the mucosal side and of 2 micrograms/ml A23187 to both the serosal and mucosal sides raised short-circuit current (Isc). This rise was reversed by serosal addition of 5 x 10(-5) M bumetanide or 10(-4) M ouabain. In filters treated with CT, Isc and net chloride flux (JClnet) increased after 60 min from 0.05 +/- 0.008 and -0.04 in the Ringer to 0.32 +/- 0.05 and -0.33 mueq.h-1.cm-2, respectively. Addition of 10(-2) M glucose further raised Isc by stimulating net sodium flux (JNanet) (0.70 +/- 0.08 and + 0.58 mueq.h-1.cm-2, respectively). This additional augmentation of Isc was reversed by 0.5 mM phlorizin and was mimicked by 3-O-methyl-D-glucose. When the filters were stimulated by cAMP for 15 min, Isc was also enhanced by addition of glucose. In untreated filters, Isc, JNanet, and JClnet did not differ significantly before and after addition of glucose. It is concluded that HRT-18 cells in basal state do not display absorptive properties but secretory properties stimulated by CT. However they exhibit Na+-glucose cotransport once stimulated by either CT or cAMP.

scholarly journals Binding of [3H]ouabain to split frog skin: the role of the Na,K-ATPase in the generation of short circuit current.

1978 ◽  
Vol 71 (4) ◽  
pp. 347-367 ◽  
Author(s):  
P M Cala ◽  
N Cogswell ◽  
L J Mandel
Keyword(s):  
Turnover Rate ◽  
Frog Skin ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Ouabain Binding ◽  
Bathing Medium ◽  
Binding Rate ◽  
Straight Line ◽  
Skin To Skin

The binding of [3H]ouabain to the serosal side was studied in a chambered preparation of frog skin, free of connective tissue, while the short circuit (Isc) was concurrently monitored. Both ouabain binding and Isc inhibition proceeded as hyperbolic functions of time. A plot of the number of ouabain molecules bound vs. the corresponding values of Isc inhibition (percent) yielded a straight line, yet showed that one-third of the binding occurred before any inhibition of Isc. Upon separation of the skins into two groups based upon initial Isc(Isci)--high, greater than 20 microamperemeter/cm2 and low, less than 10 microamperemeter/cm2, we observed two distinct populations. The high Isci skins bound very little ouabain before inhibition of Isc whereas low Isci skins bound one-half of the total number of sites before exhibiting any inhibition of Isc. These observations strongly suggest that (a) the Na,K-ATPase is directly involved in the generation of Isc, and (b) at low Isc, inhibition of some pumps by ouabain causes a "recruitment" of other pumps to increase their turnover rate and maintain Isc relatively unaffected. In addition, the binding of ouabain also displayed various characteristics that were consistent with known properties of the Na,K-ATPase: (a) increased intracellular K/Na concentrations, whether achieved through the addition of amiloride or removal of Na from the outside medium, led to a significant decrease in ouabain binding rate relative to paired controls; and (b) ouabain binding, either with normal or decreased intracellular Na, was significantly reduced in the presence of elevated K in the serosal bathing medium. Finally, the number of ouabain molecules bound to the frog skins was not correlated with their initial Isc values, indicating that the spontaneous skin-to-skin variation in Isc was not related to the number of functional pump sites but, rather, to their turnover rate.

Activation of proteinase-activated receptor-1 inhibits neurally evoked chloride secretion in the mouse colon in vitro

2005 ◽  
Vol 288 (2) ◽  
pp. G337-G345 ◽  
Author(s):  
Michelle C. Buresi ◽  
Nathalie Vergnolle ◽  
Keith A. Sharkey ◽  
Catherine M. Keenan ◽  
Patricia Andrade-Gordon ◽  
...  
Keyword(s):  
Short Circuit ◽  
Cholinergic Neurons ◽  
Short Circuit Current ◽  
Chloride Secretion ◽  
Bathing Medium ◽  
Ussing Chambers ◽  
Mouse Colon ◽  
Deficient Mice

The proteinase-activated thrombin receptor-1 (PAR-1) belongs to a unique family of G protein-coupled receptors activated by proteolytic cleavage. We studied the effect of PAR-1 activation in the regulation of ion transport in mouse colon in vitro. Expression of PAR-1 in mouse colon was assessed by RT-PCR and immunohistochemistry. To study the role of PAR-1 activation in chloride secretion, mouse colon was mounted in Ussing chambers. Changes in short-circuit current ( Isc) were measured in tissues exposed to either thrombin, saline, the PAR-1-activating peptide TFLLR-NH2, or the inactive reverse peptide RLLFT-NH2, before electrical field stimulation (EFS). Experiments were repeated in the presence of either a PAR-1 antagonist or in PAR-1-deficient mice to assess receptor specificity. In addition, studies were conducted in the presence of chloride-free buffer or the muscarinic antagonist atropine to assess chloride dependency and the role of cholinergic neurons in the PAR-1-induced effect. PAR-1 mRNA was expressed in full-thickness specimens and mucosal scrapings of mouse colon. PAR-1 immunoreactivity was found on epithelial cells and on neurons in submucosal ganglia where it was colocalized with both VIP and neuropeptide Y. After PAR-1 activation by thrombin or TFLLR-NH2, secretory responses to EFS but not those to forskolin or carbachol were significantly reduced. The reduction in the response to EFS was not observed in the presence of the PAR-1 antagonist, in PAR-1-deficient mice, when chloride was excluded from the bathing medium, or when atropine was present. PAR-1 is expressed in submucosal ganglia in the mouse colon and its activation leads to a decrease in neurally evoked epithelial chloride secretion.

Electrical properties of monolayers cultured from cells of human tracheal mucosa

1985 ◽  
Vol 58 (5) ◽  
pp. 1729-1735 ◽  
Author(s):  
J. H. Widdicombe ◽  
D. L. Coleman ◽  
W. E. Finkbeiner ◽  
I. K. Tuet
Keyword(s):  
Loop Diuretic ◽  
Apical Membrane ◽  
Short Circuit ◽  
Basolateral Membrane ◽  
Short Circuit Current ◽  
Serosal Side ◽  
Tracheal Mucosa ◽  
Isolated Cells ◽  
Trypan Blue Exclusion ◽  
Mucosal Side

Dispersed isolated cells were obtained from human tracheal mucosa by digestion with collagenase. Up to 1.5 X 10(8) cells were obtained per trachea and showed up to 95% viability, as judged by trypan blue exclusion. When grown in culture, the cells formed monolayers after approximately 4 days. Electron microscopy of the monolayers revealed a polarized structure. An apical membrane, containing microvilli and a pronounced glycocalyx, was separated from a relatively unspecialized basolateral membrane by typical tight junctions. Monolayers grown on nucleopore filters showed resistances of 44–1,800 omega. cm2 and transepithelial potential differences of 0.1–7.6 mV. Short-circuit current (Isc) was increased by isoproterenol, prostaglandins E2 and F2 alpha, and bradykinin. The loop diuretic, bumetanide, reduced Isc when added to the basolateral (serosal) side but had no effect from the apical (mucosal) side of the monolayers. Furosemide and MK-196 also inhibited Isc. Mucosal amiloride inhibited Isc. Serosal amiloride or mucosal ouabain had no effect on Isc. Serosal ouabain brought Isc to zero after approximately 15 min.

Abstract P002: Soluble (pro)renin Receptor Contributes To Angiotensin II-Induced Hypertension In Mice

Hypertension ◽  
2020 ◽  
Vol 76 (Suppl_1) ◽  
Author(s):  
Ye Feng ◽  
Fei Wang ◽  
Kexin Peng ◽  
Yanting Chen ◽  
Renfei Luo ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Short Circuit ◽  
Ussing Chamber ◽  
Short Circuit Current ◽  
Mutant Mice ◽  
Induced Hypertension ◽  
Renin Level ◽  
Intrarenal Ras

Activation of (pro)renin receptor (PRR) contributes to enhancement of intrarenal RAS and renal medullary α-ENaC and thus elevated blood pressure during angiotensin II (AngII) infusion. Soluble PRR (sPRR), the extracellular domain of PRR, is generated by multiple proteases including furin or ADAM19, and recently site-1 protease (S1P). The goal of the present study was to test the role of S1P-derived sPRR mediated AngII-induced hypertension. F1 B6129SF1/J mice were infused for 6 days with control (CTR) or AngII at 300 ng/kg/day alone or in combination with S1P inhibitor PF-429242 (PF) and blood pressure was monitored by radiotelemetry. S1P inhibition significantly attenuated AngII-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 histadine-tagged sPRR termed as sPRR-His. Mutagenesis of overlapping recognition site for S1P and furin in PRR for was generated in mice by CRISPR strategy (termed as mutant mice). Mutant mice were fertile and developed normally with a 50% reduction plasma sPRR. These mice exhibited blunted hypertensive response to AngII infusion accompanied with suppressed intrarenal renin levels. Ussing chamber technique was performed to determine amiloride-sensitive short-circuit current, an index of ENaC activity in confluent mpkCCD cells exposed for 24 h to AngII, AngII + PF, or AngII + PF + sPRR-His. AngII-induced ENaC activity was blocked by PF, which was reversed by sPRR-His. Together, these results support that sPRR derived from S1P or in combination with furin mediates AngII-induced hypertension through enhancement of intrarenal renin level and activation of ENaC.

Effects of Bicarbonate on Salt and Water Transport Across the Intestine of the Seawater EEL

1990 ◽  
Vol 150 (1) ◽  
pp. 367-379 ◽  
Author(s):  
MASAAKI ANDO
Keyword(s):  
Phosphate Buffer ◽  
Short Circuit ◽  
Water Flux ◽  
Short Circuit Current ◽  
Buffer System ◽  
Serosal Side ◽  
Inhibitory Effects ◽  
Cotransport System ◽  
Mucosal Side ◽  
Net Water Flux

To elucidate whether the Na+/K+/Cl− cotransport system depends on HCO3− in the seawater eel intestine, the effects of HCO3− on the transepithelial potential difference (PD) and on net water and ion fluxes were examined. When HCO3− buffer was replaced with phosphate buffer, the serosa-negative PD and net Na+, Cl− and water fluxes from mucosa to serosa were inhibited, indicating that the Na+/K+/Cl− cotransport system is inhibited in phosphate-buffered solutions. Similar inhibitory effects were also observed in solutions buffered with Hepes, Tris or Tes, indicating that the inhibitory effects are not specific for the phosphate buffer but are caused by omission of the HCO3− buffer system. Although the HCO3− buffer system consists of HCO3− and CO2, higher CO2 pressure with constant HCO3− concentration did not enhance, but inhibited, the PD and the net water flux: this indicates that the inhibition observed after removal of the HCO3− buffer system is due to omission of HCO3− rather than CO2. The inhibition of PD and the net water flux was greater after removal of HCO3− from the serosal side than from the mucosal side. Similarly, the inhibitory effects of 4,4′-diisothiocyanostilbene- 2,2′-disulphonic acid (DIDS), an inhibitor of HCO3− transport, were more pronounced on the serosal side than on the mucosal side. Mucosal Ba2+ also inhibited PD and the short-circuit current (Isc) and enhanced the tissue resistance (Rt), presumably through partially blocking the apical K+ channels. However, these effects of Ba2+ were completely abolished after pretreatment with serosal DIDS, suggesting that Ba2+ and DIDS evoked the same effect. These results are combined and a possible role for HCO3− in the Na+/K+/Cl− cotransport system is discussed.

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