scholarly journals Small conductance chloride channels in the apical membrane of thyroid cells

FEBS Letters ◽  
1990 ◽  
Vol 259 (2) ◽  
pp. 263-268 ◽  
Author(s):  
G. Champigny ◽  
B. Verrier ◽  
C. Gérard ◽  
J. Mauchamp ◽  
M. Lazdunski
Keyword(s):  
Chloride Channels ◽  
Apical Membrane ◽  
Thyroid Cells ◽  
Small Conductance

Chloride channels in apical membrane of primary cultures of rabbit distal bright convoluted tubule

1994 ◽  
Vol 266 (4) ◽  
pp. F543-F553 ◽  
Author(s):  
V. Poncet ◽  
M. Tauc ◽  
M. Bidet ◽  
P. Poujeol
Keyword(s):  
Chloride Channels ◽  
Apical Membrane ◽  
Primary Cultures ◽  
Transmembrane Conductance Regulator ◽  
Patch Clamp Technique ◽  
Cl Channel ◽  
Current Voltage ◽  
Cl Channels ◽  
Inside Out ◽  
Small Conductance

Using the patch clamp technique on the apical membrane of primary cultures of rabbit distal bright convoluted tubule cells (DCTb), two types of Cl- channel were identified. A small channel of 9 pS was observed in 9% of the patches. Cells pretreated with 1 mM 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) or 5 microM forskolin increased the expression of Cl- channels by 26 and 37%, respectively. In cell-attached and excised inside-out patches, the current-voltage (I-V) relationships of the 9-pS channel were linear. In only 1 out of 47 active patches was the small-conductance Cl- channel still active 1 h after membrane excision. The addition of 0.1 microM of the catalytic subunit protein kinase A with 2 mM ATP to the cytoplasmic side restored channel activity in 8 out of 15 excised membrane patches. In 5 out of 467 patches of stimulated or nonstimulated cells, a larger Cl- conductance of 30 pS was also recorded. In excised inside-out patches this channel outwardly rectified and was activated by strong depolarization. In cultured DCTb cells, the small-conductance, cAMP-activated Cl- channel shares many properties with the cystic fibrosis transmembrane conductance regulator. Our results suggest that at least the small-conductance channel may participate in Cl- secretion across the apical membrane of DCTb in primary culture. This secretion may increase the rate of the apical Cl-/HCO3- exchange indirectly by enhancing the inwardly-directed Cl- gradient.

Sodium channel heterogeneity in the apical membrane of porcine thyroid epithelial cells

1996 ◽  
Vol 149 (1) ◽  
pp. 101-108 ◽  
Author(s):  
J R Bourke ◽  
K C Abel ◽  
G J Huxham ◽  
O Sand ◽  
S W Manley
Keyword(s):  
Epithelial Cells ◽  
High Selectivity ◽  
Apical Membrane ◽  
Prostaglandin E ◽  
Free Medium ◽  
Thyroid Cells ◽  
Cultured Epithelium ◽  
Apical Membranes ◽  
Small Conductance ◽  
High Conductance

Abstract Porcine thyroid epithelial cells cultured as a monolayer with their apical membranes facing the medium are known to absorb Na+ and secrete Cl−. Two types of Na+ channels were found in cell-attached patches of apical membrane. A low conductance Na+ channel (conductance g=4 picosiemens (pS)) remained open for seconds and showed a high selectivity for Na+ compared with K+. In contrast, a high conductance Na+ channel (g=10 pS) flickered rapidly and had reduced selectivity. Both types of Na+ channel became more prevalent when the cells were exposed to Na+-free medium, though only the high conductance channel increased in prevalence on addition of prostaglandin E2, a stimulator of adenylate cyclase which increases Na+ absorption in this cultured epithelium. Two minority types of channel were also found: a non-selective small conductance cation channel which had been reported previously, and an intermediate conductance channel found only in Na+-free medium. It was concluded that passage of Na+ across the apical membrane of thyroid cells is mediated by typical epithelial Na+ channels, but that the two types of channel are differentially regulated. Journal of Endocrinology (1996) 149, 101–108

Inhibitory effects of amiloride and its analogues on prostaglandin E2-stimulated fluid transport by cultured porcine thyroid cells: evidence for apical membrane Na+ channels

1989 ◽  
Vol 123 (1) ◽  
pp. 93-97 ◽  
Author(s):  
T. Matainaho ◽  
E. J. Cragoe ◽  
S. W. Manley ◽  
G. J. Huxham ◽  
J. V. Pearson ◽  
...  
Keyword(s):  
Fluid Transport ◽  
Apical Membrane ◽  
Dome Height ◽  
Prostaglandin E ◽  
Confidence Limits ◽  
Inhibitory Effects ◽  
Culture Dish ◽  
Basal Surface ◽  
Thyroid Cells ◽  
Transport Fluid

ABSTRACT Confluent monolayers of cultured porcine thyroid cells transport fluid from the apical to the basal surface, forming circumscribed zones of detachment (domes) from the culture dish substrate. Fluid transport, as measured by increase in dome height, was stimulated by prostaglandin E2 (PGE2; 1 μmol/l) and inhibited by amiloride (0·1–100 μmol/l). Values of the inhibition constant (Ki) with 95% confidence limits for each of a series of amiloride analogues were: 3′,4′-dichlorobenzamil (DCB), 0·090 (0·045–0·18) μmol/l; 2′,4′;-dimethylbenzamil (DMB), 0·14 (0·074–0·27) μmol/l; amiloride, 0·72 (0·33–1·8) μmol/l; 5-(N,N-hexamethylene)amiloride (HMA), 17 (5·9–43) μmol/l; 5-(N-ethyl-N-isopropyl)amiloride (EIPA), 33 (15–71) μmol/l; and 2-guanidinobenzimidazole, 243 (110–570) μmol/l. Triaminopyrimidine was ineffective at concentrations up to 1 mmol/l. Since DCB and DMB are known to have a higher affinity for Na+ channels, while HMA and EIPA show higher affinity for Na+/H+ antiports, it was concluded that PGE2-stimulated fluid transport involved an apical membrane Na+ channel. Journal of Endocrinology (1989) 123, 93–97

scholarly journals Heterogeneity of chloride channels in the apical membrane of isolated mitochondria-rich cells from toad skin.

1996 ◽  
Vol 108 (5) ◽  
pp. 421-433 ◽  
Author(s):  
J B Sørensen ◽  
E H Larsen
Keyword(s):  
Chloride Channels ◽  
Single Channel ◽  
Apical Membrane ◽  
Single Cells ◽  
Membrane Depolarization ◽  
Equilibrium Potential ◽  
Toad Skin ◽  
Patch Clamp Technique ◽  
Cl Channels ◽  
Inside Out

The isolated epithelium of toad skin was disintegrated into single cells by treatment with collagenase and trypsine. Chloride channels of cell-attached and excised inside-out apical membrane-patches of mitochondria-rich cells were studied by the patch-clamp technique. The major population of Cl- channels constituted small 7-pS linear channels in symmetrical solutions (125 mM Cl-). In cell-attached and inside-out patches the single channel i/V-relationship could be described by electrodiffusion of Cl- with a Goldmann-Hodgkin-Katz permeability of, PCl = 1.2 x 10(-14) - 2.6 x 10(-14) cm3. s-1. The channel exhibited voltage-independent activity and could be activated by cAMP. This channel is a likely candidate for mediating the well known cAMP-induced transepithelial Cl- conductance of the amphibian skin epithelium. Another population of Cl- channels exhibited large, highly variable conductances (upper limit conductances, 150-550 pS) and could be activated by membrane depolarization. A group of intermediate-sized Cl(-)-channels included: (a) channels (mean conductance, 30 pS) with linear or slightly outwardly rectifying i/V-relationships and activity occurring in distinct "bursts," (b) channels (conductance-range, 10-27 pS) with marked depolarization-induced activity, and (c) channels with unresolvable kinetics. The variance of current fluctuations of such "noisy" patches exhibited a minimum close to the equilibrium-potential for Cl-. With channels occurring in only 38% of sealed patches and an even lower frequency of voltage-activated channels, the chloride conductance of the apical membrane of mitochondria-rich cells did not match quantitatively that previously estimated from macroscopic Ussing-chamber experiments. From a qualitative point of view, however, we have succeeded in demonstrating the existence of Cl-channels in the apical membrane with features comparable to macroscopic predictions, i.e., activation of channel gating by cAMP and, in a few patches, also by membrane depolarization.

Control of ion transport in the thyroid: prostaglandin E2 activates cation transport on the basal membrane of cultured porcine thyroid cell monolayers

1990 ◽  
Vol 127 (2) ◽  
pp. 197-202 ◽  
Author(s):  
J. R. Bourke ◽  
E. J. Cragoe ◽  
G. J. Huxham ◽  
J. V. Pearson ◽  
S. W. Manley
Keyword(s):  
Ion Transport ◽  
Apical Membrane ◽  
Basal Membrane ◽  
Cation Transport ◽  
Potential Difference ◽  
Prostaglandin E ◽  
Thyroid Cell ◽  
Least Squares Regression ◽  
Thyroid Cells ◽  
Stimulation Of

ABSTRACT Confluent monolayers of cultured porcine thyroid cells transport fluid from the apical to the basal surface, forming circumscribed zones of detachment (domes) from the culture dish substrate. Stimulation of fluid transport by prostaglandin E2 (PGE2; 1 μmol/l) was associated with an increase in transepithelial potential (TEP). Intracellular potentials (equal to the potential difference across the apical membrane of the cell, Eapical) and the TEP were measured in individual domes so that the potential difference across the basal membrane of the cell (Ebasal) could be calculated from the relationship TEP = Eapical − Ebasal. The PGE2-induced increase in TEP was associated with hyperpolarization of the basal membrane, accompanied by a slight depolarization of the apical membrane. Lines of best fit by least-squares regression showed Eapical = −20·3 mV + 0·219 TEP (correlation coefficient r = 0·627; P < 0·001) and Ebasal = −20·3 mV − 0·781 TEP (r = 0·944; P < 0·001). Phenamil (1 μmol/l), a Na+ channel selective amiloride analogue, reduced the TEP from 13·25±0·58 (s.e.m.; n = 56) to 2·39±0·16 mV (n = 51; P < 0·001) and hyperpolarized the apical membrane potential from − 20·7±0·68 (n = 60) to −32·2±0·83 mV (n = 105; P < 0·001). The response of the TEP to phenamil was immediate, and was promptly reversed on washing; in contrast, addition of 5-(N-ethyl-N-isopropyl)amiloride (20 μmol/l; selective for Na+/H+ antiporters) resulted in a slow depolarization over 30 min with a slow recovery after washout. Exposure of the cultures to media of pH 7·04 (compared with the normal pH of 7·34) resulted in a reduced response to PGE2, and a reduction in magnitude of Ebasal. It was concluded that stimulation of ion transport by PGE2 in thyroid monolayers involves activation of cation transport across the basal membrane. Journal of Endocrinology (1990) 127, 197–202

Anoctamin-1/TMEM16A is the major apical iodide channel of the thyrocyte

2014 ◽  
Vol 307 (12) ◽  
pp. C1102-C1112 ◽  
Author(s):  
L. Twyffels ◽  
A. Strickaert ◽  
M. Virreira ◽  
C. Massart ◽  
J. Van Sande ◽  
...  
Keyword(s):  
Cell Lines ◽  
Apical Membrane ◽  
Specific Inhibitor ◽  
Anion Channel ◽  
Thyroid Cell ◽  
Anoctamin 1 ◽  
Thyroid Cells ◽  
Rat Thyroid

Iodide is captured by thyrocytes through the Na+/I− symporter (NIS) before being released into the follicular lumen, where it is oxidized and incorporated into thyroglobulin for the production of thyroid hormones. Several reports point to pendrin as a candidate protein for iodide export from thyroid cells into the follicular lumen. Here, we show that a recently discovered Ca2+-activated anion channel, TMEM16A or anoctamin-1 (ANO1), also exports iodide from rat thyroid cell lines and from HEK 293T cells expressing human NIS and ANO1. The Ano1 mRNA is expressed in PCCl3 and FRTL-5 rat thyroid cell lines, and this expression is stimulated by thyrotropin (TSH) in rat in vivo, leading to the accumulation of the ANO1 protein at the apical membrane of thyroid follicles. Moreover, ANO1 properties, i.e., activation by intracellular calcium (i.e., by ionomycin or by ATP), low but positive affinity for pertechnetate, and nonrequirement for chloride, better fit with the iodide release characteristics of PCCl3 and FRTL-5 rat thyroid cell lines than the dissimilar properties of pendrin. Most importantly, iodide release by PCCl3 and FRTL-5 cells is efficiently blocked by T16Ainh-A01, an ANO1-specific inhibitor, and upon ANO1 knockdown by RNA interference. Finally, we show that the T16Ainh-A01 inhibitor efficiently blocks ATP-induced iodide efflux from in vitro-cultured human thyrocytes. In conclusion, our data strongly suggest that ANO1 is responsible for most of the iodide efflux across the apical membrane of thyroid cells.

scholarly journals Identification and Characterization of a Putative Human Iodide Transporter Located at the Apical Membrane of Thyrocytes

2002 ◽  
Vol 87 (7) ◽  
pp. 3500-3503 ◽  
Author(s):  
Anne-Marie Rodriguez ◽  
Barbara Perron ◽  
Ludovic Lacroix ◽  
Bernard Caillou ◽  
Gérard Leblanc ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Human Kidney ◽  
Protein Product ◽  
Sodium Iodide Symporter ◽  
Pcr Cloning ◽  
Thyroid Cells ◽  
Iodide Transport ◽  
Acid Protein

Iodide transport by thyrocytes is a two step process involving transporters located either in the basal or in the apical membranes of the cell. The sodium iodide symporter (NIS) is localized in the basolateral membrane facing the bloodstream and mediates iodide accumulation into thyrocytes. Pendrin has been proposed as an apical transporter. In order to identify new iodide transporters, we developed a PCR cloning strategy based on NIS sequence homologies. From a human kidney cDNA library, we characterized a gene, located on chromosome 12q23, that encodes a 610 amino acid protein sharing 46% identity (70% similarity) with the human NIS. Functional analysis of the protein expressed in mammalian cells indicates that it catalyzes a passive iodide transport. The protein product was immunohistochemically localized at the apical pole of the thyroid cells facing the colloid lumen. These results suggest that this new identified protein mediates iodide transport from the thyrocyte into the colloid lumen through the apical membrane. It was designated hAIT for human Apical Iodide Transporter.

Apical membrane chloride channels in a colonic cell line activated by secretory agonists

1988 ◽  
Vol 254 (4) ◽  
pp. C505-C511 ◽  
Author(s):  
D. R. Halm ◽  
G. R. Rechkemmer ◽  
R. A. Schoumacher ◽  
R. A. Frizzell
Keyword(s):  
Cell Line ◽  
Chloride Channels ◽  
Single Channel ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Anion Channel ◽  
Cell Types ◽  
Cl Channel ◽  
Evoked Activity ◽  
Apical Membranes

We characterized the anion channel responsible for the increase in apical membrane Cl secretion using a model salt-secreting epithelium, the T84 colonic cell line. The adenosine 3',5'-cyclic monophosphate (cAMP)-mediated secretagogues, prostaglandin E2, forskolin, and 8-bromo-cAMP, evoked activity of an outwardly rectifying Cl channel in previously quiet cell-attached membrane patches. The channel remained active in excised, inside-out membranes, where its single-channel conductance was 40-45 pS at 0 mV with 160 mM NaCl in pipette and bath. Selectivities were PCl/PNa = 50 and for halides I(1.8)/Br(1.4)/Cl(1.0)/F(0.4). This halide sequence illustrates that the ability of various anions to undergo transepithelial secretion is determined by the selectivity of the basolateral membrane Cl entry step rather than by the apical Cl channel. Open-channel probability increased with depolarization, an effect that would adjust the rate of Cl exit across secretory cell apical membranes with agonist-induced changes in apical membrane potential. Comparison with the properties of Cl channels detected in other cell types suggests that this cAMP-stimulated Cl channel is uniquely present in the apical membranes of salt-secreting epithelial cells.

Sign in / Sign up

Export Citation Format

Share Document