scholarly journals K+ secretion across frog skin. Induction by removal of basolateral Cl-.

1991 ◽  
Vol 97 (2) ◽  
pp. 219-243 ◽  
Author(s):  
R S Fisher ◽  
W Van Driessche
Keyword(s):  
Rana Temporaria ◽  
Noise Analysis ◽  
Basolateral Membrane ◽  
Apical Cell ◽  
Ringer Solution ◽  
Power Density Spectrum ◽  
Density Spectrum ◽  
K Secretion ◽  
Cell Depolarization ◽  
Lorentzian Component

We examined the development of K+ secretion after removing Cl- from the basolateral surface of isolated skins of Rana temporaria using noise analysis. K+ secretion was defined by the appearance of a Lorentzian component in the power density spectrum (PDS) when Ba2+ was present in the apical bath (0.5 mM). No Lorentzians were observed when tissues were bathed in control, NaCl Ringer solution. Replacement of basolateral Cl- by gluconate, nitrate, or SO4- (0-Clb) yielded Lorentzians with corner frequencies near 25 Hz, and plateau values (So) that were used to estimate the magnitude of K+ secretion through channels in the apical cell membranes of the principal cells. The response was reversible and reproducible. In contrast, removing apical Cl- did not alter the PDS. Reduction of basolateral Cl- to 11.5 mM induced Lorentzians, but with lower values of So. Inhibition of Na+ transport with amiloride or by omitting apical Na+ depressed K+ secretion but did not prevent its appearance in response to 0-Clb. Using microelectrodes, we observed depolarization of the intracellular voltage concomitant with increased resistance of the basolateral membrane after 0-Clb. Basolateral application of Ba2+ to depolarize cells also induced K+ secretion. Because apical conductance and channel density are unchanged after 0-Clb, we conclude that K+ secretion is "induced" simply by an increase of the electrical driving force for K+ exit across this membrane. Repolarization of the apical membrane after 0-Clb eliminated K+ secretion, while further depolarization increased the magnitude of the secretory current. The cell depolarization after 0-Clb is most likely caused directly by a decrease of the basolateral membrane K+ conductance. Ba2(+)-induced Lorentzians also were elicited by basolateral hypertonic solutions but with lower values of So, indicating that cell shrinkage per se could not entirely account for the response to 0-Clb and that the effects of 0-Clb may be partly related to a fall of intracellular Cl-.

Effect of mucosal halides on Ca(2+)-blockable currents through the skin of Rana ridibunda

1991 ◽  
Vol 261 (4) ◽  
pp. C650-C657 ◽  
Author(s):  
F. Lacaz-Vieira ◽  
W. Van Driessche
Keyword(s):  
Ringer Solution ◽  
Power Density Spectrum ◽  
Corner Frequency ◽  
Bathing Solution ◽  
Rana Ridibunda ◽  
Noise Component ◽  
Bathing Medium ◽  
Density Spectrum ◽  
K Current ◽  
Lorentzian Component

The present study deals with the interaction of mucosal anions with apical Ca(2+)-blockable cation channels of the skin of Rana ridibunda. The intracellular potential was depolarized by exposing the basolateral membranes to K2SO4 Ringer solution. The apical bathing medium consisted of nominal Ca(2+)-free K+ or Na+ solutions with SO4(2-), Cl-, Br-, or I- as the major anion. The effects of mucosal anion substitutions were studied by analyzing 1) the fluctuation in K+ current across the apical membrane driven by imposed transepithelial clamping potentials and 2) alterations of the transepithelial current (It) and conductance (Gt) as well as the Lorentzian parameters in response to anion substitution in the mucosal bathing solution. It and current noise spectra were recorded at different transepithelial potentials (Vt). A Lorentzian component was present in the power density spectrum when Vt was clamped at mucosa-positive voltages. Such noise components were never observed with mucosa-negative potentials. These findings suggest a rectifying behavior of the transepithelial cation currents. The Lorentzian noise component and the inward-oriented cation currents were depressed by the addition of micromolar concentrations of Ca2+ to the apical solutions as well as by replacing mucosal K+ or Na+ by N-methyl-D-glucamine. The Ca(2+)-blockable current and Lorentzian noise plateau (So) were gradually increased by raising Vt. Both parameters, as well as the corner frequency (fc), depended strongly on the major anion species in the apical solution; replacing mucosal SO4(2-) by one of the halides tested reduced fc and elevated So, It, and Gt considerably.

Osmotically induced basolateral K+ conductance in turtle colon: lidocaine-induced K+ channel noise

1988 ◽  
Vol 254 (1) ◽  
pp. C165-C174 ◽  
Author(s):  
D. C. Dawson ◽  
W. Van Driessche ◽  
S. I. Helman
Keyword(s):  
Single Channel ◽  
Basolateral Membrane ◽  
Power Density Spectrum ◽  
Corner Frequency ◽  
Cell Swelling ◽  
Channel Noise ◽  
K Channel ◽  
Density Spectrum ◽  
Colonic Cells ◽  
Lorentzian Component

The basolateral membrane of amphotericin-treated turtle colon can exhibit two distinct types of K+ conductance, one of which is associated with cell swelling and is blocked by quinidine or lidocaine. Fluctuations in basolateral K+ currents were analyzed under swelling (mucosal KCl) and nonswelling (mucosal K gluconate) conditions. Under nonswelling conditions, it was not possible to detect a spontaneous Lorentzian component in the power density spectrum (PDS) and the addition of lidocaine neither inhibited the macroscopic current nor induced a Lorentzian component in the PDS. Under swelling conditions, however, lidocaine induced a Lorentzian component in the PDS and the corner frequency increased linearly with blocker concentration as expected for reversible blockade of the channel. The gating and conductance properties of osmotically induced channels estimated from a two-state model were similar to those determined recently in single-channel recordings from isolated colonic cells.

Dibutyryl cAMP activates bumetanide-sensitive electrolyte transport in Malpighian tubules

1991 ◽  
Vol 261 (3) ◽  
pp. C521-C529 ◽  
Author(s):  
J. L. Hegarty ◽  
B. Zhang ◽  
T. L. Pannabecker ◽  
D. H. Petzel ◽  
M. D. Baustian ◽  
...  
Keyword(s):  
Yellow Fever ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Fluid Secretion ◽  
Ringer Solution ◽  
Malpighian Tubules ◽  
Membrane Voltage ◽  
Dibutyryl Camp ◽  
K Secretion ◽  
Transepithelial Voltage

The effects of dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP) and bumetanide (both 10(-4) M) on transepithelial Na+, K+, Cl-, and fluid secretion and on tubule electrophysiology were studied in isolated Malpighian tubules of the yellow fever mosquito Aedes aegypti. Peritubular DBcAMP significantly increased Na+, Cl-, and fluid secretion but decreased K+ secretion. In DBcAMP-stimulated tubules, bumetanide caused Na+, Cl-, and fluid secretion to return to pre-cAMP control rates and K+ secretion to decrease further. Peritubular bumetanide significantly increased Na+ secretion and decreased K+ secretion so that Cl- and fluid secretion did not change. In bumetanide-treated tubules, the secretagogue effects of DBcAMP are blocked. In isolated Malpighian tubules perfused with symmetrical Ringer solution, DBcAMP significantly hyperpolarized the transepithelial voltage (VT) and depolarized the basolateral membrane voltage (Vbl) with no effect on apical membrane voltage (Va). Total transepithelial resistance (RT) and the fractional resistance of the basolateral membrane (fRbl) significantly decreased. Bumetanide also hyperpolarized VT and depolarized Vbl, however without significantly affecting RT and fRbl. Together these results suggest that, in addition to stimulating electroconductive transport, DBcAMP also activates a nonconductive bumetanide-sensitive transport system in Aedes Malpighian tubules.

Effect of amiloride on the poorly selective cation channel of larval bullfrog skin

1989 ◽  
Vol 256 (1) ◽  
pp. C168-C174 ◽  
Author(s):  
S. D. Hillyard ◽  
W. Van Driessche
Keyword(s):  
Single Channel ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Inhibitory Effect ◽  
Ringer Solution ◽  
Cation Channel ◽  
Power Density Spectrum ◽  
Corner Frequency ◽  
Open Probability ◽  
Density Spectrum

A small, inward-directed, short-circuit current (SCC) was measured across the isolated skin of larval bullfrogs (Rana catesbeiana) when either NaCl or KCl Ringer solution bathed the mucosal surface. The addition of amiloride, in concentrations of 1-100 microM, produced a stepwise increase in SCC. As SCC values became maximally elevated by amiloride, the plateau value (So) of the Lorentzian component in the power-density spectrum increased, whereas the corner frequency (fc) decreased. This agonist effect of amiloride can be explained by an increase in the open probability and possibly the single-channel current of the larval channel. When the amiloride concentration was increased above 100 microM, the SCC values declined progressively but usually remained above pretreatment values. This suggests an antagonist effect of amiloride that is concurrent with the agonist effect. The removal of Ca2+ from the mucosal Ringers increased SCC in conjunction with an increase in So and a decrease in fc. Under these conditions, the maximal agonist effect of amiloride was observed at concentrations of 10-20 microM. Ca2+ thus exerts an inhibitory effect on the larval cation channel that interferes with the agonist effect of amiloride. The addition of Ba2+ to Ca2+-free preparations lowered SCC and reduced the agonist effect of amiloride.

Analysis of fast channel blockage: revealing substrate binding in the microsecond range

The Analyst ◽  
2015 ◽  
Vol 140 (14) ◽  
pp. 4820-4827 ◽  
Author(s):  
Igor Bodrenko ◽  
Harsha Bajaj ◽  
Paolo Ruggerone ◽  
Mathias Winterhalter ◽  
Matteo Ceccarelli
Keyword(s):  
Power Density ◽  
Substrate Binding ◽  
Noise Analysis ◽  
Power Density Spectrum ◽  
Ion Currents ◽  
Density Spectrum ◽  
Real Power ◽  
The Real ◽  
Markov State ◽  
Channel Blockage

The effect of filtering can be taken into account within the Markov state description to obtain the “real” power density spectrum in noise analysis of ion currents.

Effect of forskolin on conductive anion pathways of toad skin

1992 ◽  
Vol 263 (1) ◽  
pp. C166-C171 ◽  
Author(s):  
W. Nagel ◽  
W. Van Driessche
Keyword(s):  
Quadratic Function ◽  
Power Density Spectrum ◽  
Toad Skin ◽  
Density Spectrum ◽  
Cl Transport ◽  
Conductive Pathway ◽  
Current Voltage ◽  
Current Voltage Relationship ◽  
Voltage Relationship ◽  
Lorentzian Component

The effect of the diterpene, forskolin, on pathways for conductive Cl- transport was analyzed using isolated skins of Bufo viridis. Forskolin did not stimulate the voltage-activated Cl- movement from mucosa to serosa; the Lorentzian component in the power density spectrum, which was present at serosa positive clamp potentials under control conditions, decreased significantly. The observation that stimulation of cytosolic adenosine 3'-5'-cyclic monophosphate (cAMP) by forskolin has no effect on the voltage-activated Cl- transport argues against control of this pathway by cAMP. Our data further demonstrate that the forskolin-activated Cl- conductive pathway is also permeable for NO3-. This pathway was studied in absence of mucosal Cl-, which eliminates Cl- movement through the voltage-activated pathway. With SO4(2-) and Cl- on the mucosal and serosal sides, respectively, this forskolin-induced pathway displayed a linear current-voltage relationship. The associated Lorentzians increased at serosa negative clamp potentials. Transepithelial current and plateau value of the Lorentzian were related by a quadratic function, which suggests voltage-independence of number and open-close probability of these conductance sites. Morphological sites for voltage-activated and forskolin-induced conductive Cl- transport remain to be identified.

scholarly journals Properties of Faint X-ray Activity of XTE J1908+094 in 2019

Galaxies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 25
Author(s):  
Debjit Chatterjee ◽  
Arghajit Jana ◽  
Kaushik Chatterjee ◽  
Riya Bhowmick ◽  
Sujoy Kumar Nath ◽  
...  
Keyword(s):  
Black Hole ◽  
Temporal Analysis ◽  
Power Density Spectrum ◽  
Periodic Oscillations ◽  
Telescope Array ◽  
Density Spectrum ◽  
X Ray ◽  
Black Hole Candidate ◽  
Short Period ◽  
Spectral State

We study the properties of the faint X-ray activity of Galactic transient black hole candidate XTE J1908+094 during its 2019 outburst. Here, we report the results of detailed spectral and temporal analysis during this outburst using observations from Nuclear Spectroscopic Telescope Array (NuSTAR). We have not observed any quasi-periodic-oscillations (QPOs) in the power density spectrum (PDS). The spectral study suggests that the source remained in the softer (more precisely, in the soft–intermediate) spectral state during this short period of X-ray activity. We notice a faint but broad Fe Kα emission line at around 6.5 keV. We also estimate the probable mass of the black hole to be 6.5−0.7+0.5M⊙, with 90% confidence.

scholarly journals (Na+ + K+)-ATPase and plasma membrane polarity of intestinal epithelial cells: presence of a brush border antigen in the distal large intestine that is immunologically related to beta subunit.

1989 ◽  
Vol 109 (3) ◽  
pp. 1057-1069 ◽  
Author(s):  
A Marxer ◽  
B Stieger ◽  
A Quaroni ◽  
M Kashgarian ◽  
H P Hauri
Keyword(s):  
Monoclonal Antibody ◽  
Small Intestine ◽  
Epithelial Cells ◽  
Brush Border ◽  
Basolateral Membrane ◽  
Apical Cell ◽  
Distal Colon ◽  
Proximal Colon ◽  
Beta Subunit ◽  
Cell Pole

The previously produced monoclonal antibody IEC 1/48 against cultured rat intestinal crypt cells (Quaroni, A., and K. J. Isselbacher. 1981. J. Natl. Cancer Inst. 67:1353-1362) was extensively characterized and found to be directed against the beta subunit of (Na+ + K+)-ATPase as assessed by immunological and enzymatic criteria. Under nondenaturing conditions the antibody precipitated the alpha-beta enzyme complex (98,000 and 48,000 Mr). This probe, together with the monoclonal antibody C 62.4 against the alpha subunit (Kashgarian, M., D. Biemesderfer, M. Caplan, and B. Forbush. 1985. Kidney Int. 28:899-913), was used to localize (Na+ + K+)-ATPase in epithelial cells along the rat intestinal tract by immunofluorescence and immunoelectron microscopy. Both antibodies exclusively labeled the basolateral membrane of small intestine and proximal colon epithelial cells. However, in the distal colon, IEC 1/48, but not C 62.4, also labeled the brush border membrane. The cross-reacting beta-subunit-like antigen on the apical cell pole was tightly associated with isolated brush borders but was apparently devoid of (Na+ + K+)-ATPase activity. Subcellular fractionation of colonocytes in conjunction with limited proteolysis and surface radioiodination of intestinal segments suggested that the cross-reacting antigen in the brush border may be very similar to the beta subunit. The results support the notion that in the small intestine and proximal colon the enzyme subunits are exclusively targeted to the basolateral membrane while in the distal colon nonassembled beta subunit or a beta-subunit-like protein is also transported to the apical cell pole.

scholarly journals RECOGNIZING DIFFERENT TYPES OF STOCHASTIC PROCESSES

2006 ◽  
Vol 06 (01) ◽  
pp. L1-L6
Author(s):  
JONG U. KIM ◽  
LASZLO B. KISH
Keyword(s):  
Image Processing ◽  
Stochastic Processes ◽  
Cross Correlation ◽  
Correlation Method ◽  
Correlation Coefficients ◽  
Power Density Spectrum ◽  
Density Spectrum ◽  
Random Telegraph Signals ◽  
Different Types ◽  
Coefficient Method

We propose a new cross-correlation method that can recognize independent realizations of the same type of stochastic processes and can be used as a new kind of pattern recognition tool in biometrics, sensing, forensic, security and image processing applications. The method, which we call bispectrum correlation coefficient method, makes use of the cross-correlation of the bispectra. Three kinds of cross-correlation coefficients are introduced. To demonstrate the new method, six different random telegraph signals are tested, where four of them have the same power density spectrum. It is shown that the three coefficients can map the different stochastic processes to specific sub-volumes in a cube.

Activation of CFTR Cl- conductance in polarized T84 cells by luminal extracellular ATP

1995 ◽  
Vol 268 (2) ◽  
pp. C425-C433 ◽  
Author(s):  
M. J. Stutts ◽  
E. R. Lazarowski ◽  
A. M. Paradiso ◽  
R. C. Boucher
Keyword(s):  
Adenosine Receptor ◽  
Apical Membrane ◽  
Short Circuit ◽  
Basolateral Membrane ◽  
Apical Cell ◽  
Extracellular Atp ◽  
T84 Cells ◽  
Apical Cell Membrane ◽  
Cl Secretion ◽  
Cl Conductance

Luminal extracellular ATP evoked a bumetanide-sensitive short-circuit current in cultured T84 cell epithelia (90.2 +/- 18.2 microA/cm2 at 100 microM ATP, apparent 50% effective concentration, 11.5 microM). ATP appeared to increase the Cl- conductance of the apical membrane but not the driving force for Cl- secretion determined by basolateral membrane K+ conductance. Specifically, the magnitude of Cl- secretion stimulated by ATP was independent of basal current, and forskolin pretreatment abolished subsequent stimulation of Cl- secretion by ATP. Whereas ATP stimulated modest production of adenosine 3',5'-cyclic monophosphate (cAMP) by T84 cells, ATP caused smaller increases in intracellular Ca2+ and inositol phosphate activities than the Ca(2+)-signaling Cl- secretagogue carbachol. An inhibitor of 5'-nucleotidase, alpha,beta-methyleneadenosine 5'-diphosphate, blocked most of the response to luminal ATP. The adenosine receptor antagonist 8-(p-sulfophenyl)theophylline blocked both the luminal ATP-dependent generation of cAMP and Cl- secretion when administered to the luminal but not submucosal bath. These results demonstrate that the Cl- secretion stimulated by luminal ATP is mediated by a A2-adenosine receptor located on the apical cell membrane. Thus metabolism of extracellular ATP to adenosine regulates the activity of cystic fibrosis transmembrane conductor regulator (CFTR) in the apical membrane of polarized T84 cells.

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