Extracellular cGMP inhibits transepithelial sodium transport by LLC-PK1 renal tubular cells

1996 ◽  
Vol 270 (2) ◽  
pp. F283-F288 ◽  
Author(s):  
R. L. Chevalier ◽  
G. D. Fang ◽  
M. Garmey
Keyword(s):  
Sodium Transport ◽  
Short Circuit ◽  
Organic Anion ◽  
Short Circuit Current ◽  
Sodium Reabsorption ◽  
Cell Monolayers ◽  
Cyclic Monophosphate ◽  
Renal Tubular Cells ◽  
Renal Tubular ◽  
Transepithelial Sodium Transport

Both atrial natriuretic peptide (ANP) and sodium nitroprusside (SNP) inhibit tubular sodium reabsorption by generation of guanosine 3',5'-cyclic monophosphate (cGMP). To determine the role of extracellular cGMP in this response, monolayers of porcine renal tubular LLC-PK1 cells were incubated for 5 min with ANP, SNP, cGMP, or 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP) (10 nM to 0.1 mM). Transepithelial sodium transport was measured as amiloride-inhibitable short-circuit current (Isc). Incubation of cell monolayers with 1 microM of ANP, cGMP, or 8-BrcGMP inhibited Isc by > 70%, as did SNP at 100 microM (P < 0.01). Adenosine 3',5'-cyclic monophosphate (0.1 mM) had no significant effect. Incubation of monolayers with 1 microM LY-83583 (an inhibitor of guanylyl cyclase), 10 microM probenecid (an organic anion transport inhibitor), or preincubation with 1 microgram/ml nocodazole (a microtubule disrupter) reduced extracellular accumulation of cGMP (P < 0.05) and abolished the SNP-mediated reduction of Isc. However, addition of these inhibitors did not affect reduction of Isc by exogenous cGMP. We conclude that SNP inhibits sodium transport by LLC-PK1 monolayers through generation of cGMP but that extrusion of cGMP out the cell is necessary for its effect.

Effect of carbenoxolone on glucocorticoid metabolism and Na transport in toad bladder

1989 ◽  
Vol 257 (4) ◽  
pp. F700-F704
Author(s):  
A. S. Brem ◽  
K. L. Matheson ◽  
T. Conca ◽  
D. J. Morris
Keyword(s):  
Sodium Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Water Soluble ◽  
Toad Bladder ◽  
Toad Urinary Bladder ◽  
Base Line ◽  
Target Tissue ◽  
Glucocorticoid Metabolism ◽  
Transepithelial Sodium Transport

In humans, diminished 11 beta-hydroxysteroid dehydrogenase (11 beta-OHSD) enzyme activity has been associated with sodium retention and hypertension. These studies show that the toad bladder, another target tissue epithelium displaying steroid-induced sodium transport, possesses the enzyme 11 beta-OHSD. The toad urinary bladder rapidly transformed corticosterone (3 x 10(-8) M) (50% by 10 min and 90% by 180 min) with 11-dehydrocorticosterone being the major metabolite. The 11-dehydrocorticosterone produced reached an apparent plateau when the tissue incubations were repeated with higher concentrations of corticosterone (10(-7) and 10(-6) M). Carbenoxolone sodium (2.5 x 10(-5) M), a water soluble derivative of glycyrrhetinic acid, markedly inhibited the metabolism of corticosterone (3 x 10(-8) M) to 11-dehydrocorticosterone similar to previous observations in the mammalian kidney. Carbenoxolone sodium (2.5 x 10(-5) M) did not significantly affect short-circuit current (SCC) in toad bladders when added to either the serosal or mucosal bath. However, when carbenoxolone sodium was added to the mucosal bath and 60 min later corticosterone 10(-6) M was placed in the serosal bath, bladders generated a SCC 2.07 +/- 0.17 (mean +/- SE) times above base line at 360 min compared with 1.48 +/- 0.11 in bladders exposed to corticosterone alone (P less than 0.02). In parallel experiments, carbenoxolone sodium in the mucosal bath enhanced the rise in SCC induced by cortisol 10(-6) M; 1.66 +/- 0.16 times above base line at 360 min compared with 1.07 +/- 0.14 with cortisol alone (P less than 0.02). We conclude that the toad bladder contains 11 beta-OHSD and inhibition of this enzyme with carbenoxolone sodium is associated with amplification of glucocorticoid-induced transepithelial sodium transport in this tissue. However, since the quantity of 11-dehydro-product produced appears to be limited, other factors in addition to inhibition of 11 beta-OHSD may play a role in this amplification of sodium transport.

Mineralocorticoid activity of 19-nor-DOC and 19-OH-DOC in toad bladder

1981 ◽  
Vol 241 (5) ◽  
pp. E406-E409 ◽  
Author(s):  
R. D. Perrone ◽  
J. H. Schwartz ◽  
H. H. Bengele ◽  
S. L. Dale ◽  
J. C. Melby ◽  
...  
Keyword(s):  
Sodium Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Toad Bladder ◽  
Sodium Reabsorption ◽  
Sodium Retention ◽  
Onset Of Action ◽  
Mineralocorticoid Activity

Adrenal enucleation is followed by a period of increased sodium reabsorption thought to be due to excess mineralocorticoid activity. However, it has not been demonstrated that increased production of any known mineralocorticoid accounts for this antinatriuresis. Recently, 19-hydroxydeoxycorticosterone (19-OH-DOC) was found in incubates of regenerating adrenal capsules 3-4 days postenucleation and 19-nordeoxycorticosterone (19-nor-DOC) was identified in the urine of rats with regenerating adrenals. Because it was possible that these hormones might play a role in the sodium retention after adrenal enucleation, we compared the mineralocorticoid activity of these steroids to aldosterone using the toad bladder. Using short-circuit current as a measure of sodium transport, we found that 19-OH-DOC (10(-8) M) had no significant effect on sodium transport. However, 19-nor-DOC (10(-8) M) increased sodium transport to a degree not different from aldosterone (10(-8) M). Furthermore, the onset of action, duration of activity, and inhibition of effect of 19-nor-DOC by spironolactone were not different from that of aldosterone. We conclude that 19-nor-DOC exhibits a significant effect on sodium transport and thus has the potential to play a role in the sodium retention following adrenal enucleation. Under the conditions of these studies, 19-OH-DOC exhibited no effect on sodium transport.

Adenylyl cyclase is involved in desensitization and recovery of ATP-stimulated Cl−secretion in MDCK cells

1998 ◽  
Vol 274 (2) ◽  
pp. C371-C378 ◽  
Author(s):  
Jae Suk Woo ◽  
Chiyoko N. Inoue ◽  
Kazushige Hanaoka ◽  
Erik M. Schwiebert ◽  
Sandra E. Guggino ◽  
...  
Keyword(s):  
Adenylyl Cyclase ◽  
Enzyme Inhibitors ◽  
Mdck Cells ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Channel Blockers ◽  
Cell Monolayers ◽  
Cyclic Monophosphate ◽  
Recovery Processes ◽  
Darby Canine Kidney

We investigated the process of and recovery from desensitization of the P2 receptor-mediated stimulation of Cl− secretion in Madin-Darby canine kidney (MDCK) cell monolayers by assaying the response of short-circuit current ( I sc). When the cells were exposed to repeated 3-min challenges of ATP or UTP interspersed with 5-min washes, the response of I sc desensitized rapidly followed by spontaneous recovery. The pattern of inhibition by various channel blockers or enzyme inhibitors revealed that both the initial and recovered responses of I sc have the same ionic and signaling mechanisms. The desensitization and recovery processes were confined to the membrane exposed to the repeated challenges. When added during the desensitized phase, 8-bromoadenosine 3′,5′-cyclic monophosphate enhanced the ATP-stimulated I sc response, whereas it did not during the initial or recovered phases. ATP-induced increases of intracellular adenosine 3′,5′-cyclic monophosphate showed similar desensitization and recovery in parallel with the changes in the responses of I sc. The desensitization process was attenuated by pretreatment with cholera toxin or pertussis toxin. Taken together, our results suggest that the adenylyl cyclase system plays a role in the desensitization and recovery mechanism of the ATP-stimulated Cl− secretion in MDCK cells.

Oxygen metabolites modulate sodium transport in gerbil middle ear epithelium: involvement of PGE2

1995 ◽  
Vol 268 (3) ◽  
pp. L390-L398 ◽  
Author(s):  
P. Herman ◽  
T. Y. Tu ◽  
A. Loiseau ◽  
C. Clerici ◽  
R. Cassingena ◽  
...  
Keyword(s):  
Middle Ear ◽  
Sodium Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Camp Content ◽  
Respiratory Epithelia ◽  
Pg E2 ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Transepithelial Sodium Transport

The middle ear epithelium and respiratory epithelia share basic properties such as homeostasis of air-filled cavities and mucociliary clearance toward the pharynx. With the middle ear SV40-transformed (MESV) cell line, we used the short-circuit current (Isc) technique to investigate changes in ion transport induced by oxidants. Xanthine and xanthine oxidase on the basal side of the monolayers dramatically increased Isc up to 50%. This effect was not affected by superoxide dismutase or mannitol, but could be blunted by catalase or 1,3-dimethyl-2-thiourea. Increasing concentrations of H2O2 from 10(-5) to 5 x 10(-4) M produced a dose-dependent increase in Isc from 0.26 +/- 0.16 up to 4.21 +/- 0.43 microA/cm2 (P < 0.05, n = 5). Concentration of half-maximal stimulation (EC50) was 4.68 x 10(-5) M. This effect was inhibited by indomethacin and was related to a sodium transport, since the H2O2-induced increase in Isc could be prevented or abolished by 1) apical addition of benzamil (10(-6)M) and 2) substitution of sodium with N-methyl-glucamine. H2O2 exposure also induced indomethacin-sensitive increase in released prostaglandin (PG) E2 (EC50 = 5.62 x 10(-5) M) and in cAMP content (EC50 = 3.95 x 10(-5) M) with similar kinetics. These results suggest that exposure of MESV cells to oxidants stimulates the production of PGE2, which in turn increases the transepithelial sodium transport rate.

11-Dehydrocorticosterone, a glucocorticoid metabolite, inhibits aldosterone action in toad bladder

1991 ◽  
Vol 261 (5) ◽  
pp. F873-F879 ◽  
Author(s):  
A. S. Brem ◽  
K. L. Matheson ◽  
J. L. Barnes ◽  
D. J. Morris
Keyword(s):  
Sodium Transport ◽  
Cell Layer ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Hydroxysteroid Dehydrogenase ◽  
Toad Bladder ◽  
Compound A ◽  
Dose Dependent Fashion ◽  
Epithelial Cell Layer ◽  
Dose Dependent

The enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta-OHSD) metabolizes glucocorticoid hormones and diminishes their ability to induce sodium transport. In these studies, we determined the location of this enzyme in toad bladder and assessed the biological role for its 11-dehydro end product. Employing a polyclonal antibody directed toward 11 beta-OHSD and immunofluorescence techniques, we located the enzyme in the epithelial cell layer of the toad bladder. Although corticosterone (10(-7) M) can partially suppress aldosterone (10(-7) M)-stimulated short-circuit current (SCC), a clear excess of corticosterone (10(-6) M) did not inhibit the aldosterone-induced induced (10(-8) M) rise in SCC (n = 6). The 11-dehydro product of corticosterone, 11-dehydrocorticosterone (compound A) added to the serosal bath suppressed aldosterone (10(-8) M) peak SCC (360 min) in a dose-dependent fashion reaching 46 +/- 5% of control values at 10(-5) M (n = 6; P less than 0.001). Compound A (10(-5) M) in the mucosal bath also was capable of partially inhibiting the peak aldosterone rise in SCC to 63 +/- 7% of control values with aldosterone at 10(-8) M (n = 6; P less than 0.01) and to 64 +/- 10% of control values with aldosterone at 10(-7) M (n = 9; P less than 0.01). Compound A alone at 10(-5) M did not have any effect on SCC. Isolated toad bladders were not able to transform compound A (at 10(-8) and 10(-5) M) back to corticosterone. Thus the 11-dehydro end product of 11 beta-OHSD (compound A) may play a biologic role by regulating a component of mineralocorticoid-induced sodium transport.

Localization of heparin and low-molecular-weight heparin in the rat kidney

2004 ◽  
Vol 91 (05) ◽  
pp. 927-934 ◽  
Author(s):  
Vivian Douros ◽  
Thomas Podor ◽  
Stephen Shaughnessy ◽  
Jeffrey Weitz ◽  
Edward Young
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Rat Kidney ◽  
Organic Anion ◽  
Molecular Size ◽  
Immunohistochemical Analysis ◽  
Immunoperoxidase Staining ◽  
Low Molecular Weight ◽  
Renal Tubular Cells ◽  
Renal Tubular

SummaryUnfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) are cleared, at least in part, by the kidneys through a poorly understood process. This study was undertaken to explore the mechanism of renal clearance of these drugs. Rats were given fluorescein-5-isothiocyanate (FITC)-labeled UFH or LMWH intravenously. At intervals after injection, rats were euthanized and the kidneys were harvested and subjected to immunohistochemical analysis and fluorescence microscopy. Both UFH and LMWH were localized to renal tubular cells and no immunoperoxidase staining or fluorescence was detected in glomeruli. Autoradiography demonstrated similar intracellular distribution of radio-labeled UFH suggesting that this phenomenon is independent of the method used to label heparin. Fluoresence in the tubules increased as a function of time after UFH injection, but reached a plateau after LMWH injection suggesting that the rate of renal tubular uptake depends on the molecular size of the heparin. When administered prior to FITC-labeled UFH or LMWH, probenecid, a renal organic anion inhibitor, decreased the renal tubular uptake of the heparins, whereas cimetidine, a renal organic cation inhibitor, had no effect. These findings suggest that renal excretion of UFH and LMWH primarily reflects tubular uptake via an organic anion transport mechanism.

Sodium transport by lamb proximal colon measured during early postnatal development

1982 ◽  
Vol 98 (1) ◽  
pp. 155-159 ◽  
Author(s):  
M. W. Smith ◽  
P. S. James
Keyword(s):  
Postnatal Development ◽  
Sodium Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Proximal Colon ◽  
Early Postnatal Development ◽  
The Third ◽  
Electrolyte Absorption ◽  
Chloride Absorption

SUMMARYProximal colons taken from lambs up to 3 weeks after birth were shown to transport both sodium and chloride from lumen to blood when incubated in vitro.Sodium transport fell into three phases during postnatal development. The first covered the period from birth to 3 days of age when sodium transport was high and equal to that calculated from measurement of short-circuit current. The second was seen in 5- and 7-day-old lambs where the short-circuit current was low and the net transport of sodium was negligible. The third was seen in 2-3-week-old lambs where sodium transport was high, but the short-circuit current was low.Chloride absorption by colons taken from 1-day-old lambs appeared to be in exchange for an anion, possibly bicarbonate. Chloride absorption by colons taken from 3-week-old lambs appeared to be electrogenie or coupled directly to the transport of sodium.A possible explanation for the failure of electrolyte absorption by colons taken from 5- and 7-day-old lambs is discussed.

Activation of KCNQ (KV7) K+ channels in enteric neurons inhibits epithelial Cl- secretion in mouse distal colon

2021 ◽  
Author(s):  
Andrew J. Nickerson ◽  
Trey S. Rottgen ◽  
Vazhaikkurichi M. Rajendran
Keyword(s):  
Short Circuit ◽  
Short Circuit Current ◽  
Distal Colon ◽  
Therapeutic Benefit ◽  
Enteric Neurons ◽  
Intestinal Epithelial ◽  
Cell Monolayers ◽  
Neuronal Populations ◽  
Irritable Bowel

KV7 (KCNQ) K+ channels are expressed in many neuronal populations, and play an important role in regulating membrane potential by generating a hyper-polarizing K+ current and decreasing cell excitability. However, the role of KV7 channels in the neural regulation of intestinal epithelial Cl- secretion is not known. Cl- secretion in mouse distal colon was measured as a function of short circuit current (ISC), while pharmacological approaches were used to test the hypothesis that activation of KV7 channels in enteric neurons would inhibit epithelial Cl- secretion. Flupirtine, a non-selective KV7 activator, inhibited basal Cl- secretion in mouse distal colon and abolished or attenuated the effects of drugs that target various components of enteric neurotransmission, including tetrodotoxin (NaV channel blocker), Veratridine (NaV channel activator), Nicotine (nicotinic acetylcholine receptor agonist) and Hexamethonium (nicotinic antagonist). In contrast, flupritine did not block the response to epithelium-targeted agents VIP (endogenous VPAC receptor ligand) or carbachol (non-selective cholinergic agonist). Flupirtine inhibited Cl- secretion in both full-thickness and seromuscular-stripped distal colon (containing the submucosal, but not myenteric plexus), but generated no response in epithelial T84 cell monolayers. KV7.2 and KV7.3 channel proteins were detected by immunofluorescence in whole-mount preparations of the submucosa from mouse distal colon. ICA 110381 (KV7.2/7.3 specific activator) inhibited Cl- secretion comparably to flupirtine. We conclude that KV7 channel activators inhibit neurally-driven Cl- secretion in the colonic epithelium, and may therefore have therapeutic benefit in treating pathologies associated with hyper-excitable enteric nervous system, such as irritable bowel syndrome with diarrhea (IBS-D).

Aldosterone-stimulated transmethylations are linked to sodium transport

1985 ◽  
Vol 248 (1) ◽  
pp. F43-F47 ◽  
Author(s):  
W. P. Wiesmann ◽  
J. P. Johnson ◽  
G. A. Miura ◽  
P. K. Chaing
Keyword(s):  
Epithelial Cells ◽  
Sodium Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Toad Bladder ◽  
Methylation Inhibitor ◽  
In Cells

The effect of aldosterone (Aldo) on phospholipid (PL) biosynthesis in cultured toad bladder epithelial cells was studied in cells incubated with [1,2-14C]choline and [methyl-3H]methionine over a 5-h period. Aldo (10(-7) M) did not alter the uptake of either precursor but significantly stimulated the incorporation of both labels into phosphatidylcholine (PC), the only PL labeled. 3H labeling of PC increased 29% and 14C incorporation into PC increased 34% in cells exposed to Aldo. A similar 30% increase in protein carboxymethylation occurred in cells treated with Aldo. 3-Deazaadenosine (DZA), a methylation inhibitor, abolished the Aldo-stimulated increase in PC labeling from [3H]methionine. PC labeling from [1,2-14C]choline was not affected by DZA. Basal and Aldo-stimulated protein carboxy-methylation were inhibited by DZA. DZA (300 microM) caused a mild decrease in basal short-circuit current (ISC) but completely inhibited the ISC response to 10(-7) M Aldo. Inhibition was complete when DZA was added up to 2 h following exposure to Aldo, and was reversible. Cells previously exposed to Aldo showed a significant increase in ISC within 2 h following removal of DZA. We conclude that Aldo stimulates PL methylation, protein carboxymethylation, and turnover of PC from choline. Inhibition of methylation reactions coincides with the inhibition of ISC response to Aldo.

Anterior pituitary control of active sodium transport across frog skin

1961 ◽  
Vol 200 (3) ◽  
pp. 444-450 ◽  
Author(s):  
R. M. Myers ◽  
W. R. Bishop ◽  
B. T. Scheer
Keyword(s):  
Sodium Transport ◽  
Rana Pipiens ◽  
Sodium Current ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Anterior Lobe ◽  
Sodium Ion ◽  
Resting Potential ◽  
Active Sodium ◽  
Active Sodium Transport

Removal of the anterior lobe of the pituitary from the frog Rana pipiens is followed by an increase in the outflux of Na22 across the skin, which persists at least 4 months, and by a decrease in resting potential and sodium (‘short-circuit’) current, which persists no more than 3 weeks. The increased outflux is interpreted as resulting from increased permeability of the skin to sodium ion, and the decreased sodium current is interpreted as a decreased rate of active sodium transport. Either change is opposed by treatment with mammalian ACTH or with aldosterone. Effects of other hormones could not be established with certainty. The increased permeability of the skin to sodium appears to be associated with a decrease in the amount of a mucopolysaccharide in the dermis. The evidence suggests that the pituitary effects involve the interrenal bodies.

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