Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Cyclic GMP regulation of a voltage-activated K channel in dissociated Enterocytes (1991)
    Springer
    The journal of membrane biology 124 (1991), S. 159-167 
    Details
    ISSN: 1432-1424
    Keywords: cGMP ; charybdotoxin ; K recycling ; K secretion ; NaCl absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Enterrocytes from the intestinal epithelium of the winter flounder were isolated by collagenase digestion and incubated in flounder Ringer solution. Conventional whole-cell and amphotericin-perforated whole-cell recording techniques were used to characterize the properties of a voltage-activated K current present in dissociated cells. Resting membrane potentials and series resistances were significantly lower (from −23 to − 39 mV and 29 to 13 MΩ, respectively) when amphotericin was used to achieve the whole-cell configuration. When cells were placed in flounder Ringer solution, held at −80 mV and subsequently stepped to a series of depolarizing voltages (from−70 to 0 mV), an outward current was observed that exhibited inactivation at voltages above −20 mV. This current was sensitive to holding potential and was not activated when the cells were held at −40 mV or above. When cells were bathed in symmetric K Ringer solution and the same voltage protocol was applied to the cell, inward currents were observed in response to the negative intracellular potentials. Reversal potentials at two different extracellular K concentrations were consistent with K as the currentcarrying ion. BaCl2 (2 mM) and CsCl (0.5 mM) both produced voltage-dependent blockade of the current when added to the bathing solution. Charybdotoxin (300 nM extracellular concentration) completely blocked the current. The IC50 for charybdotoxin was 50 nM. Cyclic. GMP inhibited the voltage-activated current in flounder Ringer and in symmetric K Ringer solution. The cyclic GMP analog, 8-Br cGMP, lowered the threshold for voltage activation and potentiated inactivation of the current at voltages above−40 mV. Previous studies with intact flounder epithelium showed that K recycling and net K secretion were inhibited by Ba2+ and by cGMP. We suggest that the channel responsible for the whole-cell current described in this study may be important in K recycling and secretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01870460
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Mechanisms of Na and Cl absorption across the distal colon epithelium of the pig (1992)
    Springer
    Journal of comparative physiology 162 (1992), S. 47-53 
    Details
    ISSN: 1432-136X
    Keywords: Ion transport ; NaCl absorption ; Na channels ; Cl-HCO3 exchange ; Na-H exchange ; HCO3 transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Porcine distal colon epithelium was mounted in Ussing chambers and bathed in plasma-like Ringer solution. Tissue conductances ranged from 10 to 15 mS and the short-circuit current (Isc) ranged from-15 to 220 μA·cm-2. Variations in basal Isc resulted from differences in the amount of amiloride (10μM mucosal addition)-sensitive Na+ absorption. Ion substitution and transepithelial flux experiments showed that 10 μM amiloride produced a decrease in the mucosal-to-serosal (M-S) and net Na flux, and that this effect on Isc was independent of Cl- and HCO 3 - replacement. When the concentration of mucosal amiloride was increased from 10 to 100 μM, little change in Isc was observed. However, increasing the concentration to 1 mM produced a further inhibition, which often reversed the polarity of the Isc. The decrease in Isc due to 1 mM amiloride was dependent on both Cl- and HCO 3 - , and was attributed to reductions in the M-S and net Na+ fluxes as well as the M-S unidirectional Cl- flux. Ion replacement experiments demonstrated that Cl- substitution reduced the M-S and net Na fluxes, while replacement of HCO 3 - with HEPES abolished net Cl- absorption by reducing the M-S unidirectional Cl- flux. From these data it can be concluded that: (1) Na+ absorption is mediated by two distinct amiloride-sensitive transport pathways, and (2) Cl- absorption is completely HCO 3 - -dependent (presumably mediated by Cl-/HCO 3 - exchange) and occurs independently of Na+ absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00257935
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...