These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Ion transport across posterior gills of hyperosmoregulating shore crabs (Carcinus maenas): amiloride blocks the cuticular Na(+) conductance and induces current-noise.
    Author: Onken H, Riestenpatt S.
    Journal: J Exp Biol; 2002 Feb; 205(Pt 4):523-31. PubMed ID: 11893766.
    Abstract:
    Split gill lamellae and gill cuticles of shore crabs (Carcinus maenas) adapted to 10 per thousand salinity were mounted in a modified Ussing-type chamber. With NaCl saline on both sides, split gill lamellae generated a short-circuit current (I(sc)) of -301+/-16 microA cm(-2) at a conductance (G(te)) of 40+/-2 mS cm(-2). The net influxes of Na(+) and Cl(-) were 8.3+/-2.6 and 18.2+/-2.7 micromol cm(-2) h(-1), respectively. External amiloride (100 micromol l(-1)) reduced G(te) to approximately 50 % of the original value at unchanged I(sc); Cl(-) fluxes remained unaffected, whereas Na(+) fluxes were markedly reduced by 70-80 %. The I(sc) in the presence of external amiloride was almost completely inhibited by internal ouabain. At a clamp voltage of 50 mV (outside-positive), a positive current was measured at unchanged G(te). Under these conditions, amiloride reduced the current and conductance at half-maximal concentrations of 3.6 and 2.0 micromol l(-1), respectively. At outside-positive voltages, but not under short-circuit conditions, external amiloride induced Lorentzian components in the power density spectra. The amiloride-dependent changes in the corner frequency (linear) and of the low-frequency plateau ('bell-shaped') were as expected for channel blockade by amiloride with pseudo-first-order kinetics. With an outside-positive clamp voltage of 50 mV across isolated cuticles, a positive cuticular current (I(cut)) of 25 188+/-3791 microA cm(-2) and a cuticular conductance (G(cut)) of 547+/-76 mS cm(-2) were measured. External amiloride reduced I(cut) and G(cut) at half-maximal concentrations of 0.7 and 0.6 micromol l(-1), respectively. Amiloride-induced current-noise analysis gave similar results to those observed with split gill lamellae. Ion-substitution experiments with isolated cuticles further support inhibition by external amiloride of the cuticular Na(+) conductance of shore crab gills and not amiloride-sensitive transporters (Na(+) channels or Na(+)/H(+) antiports) in the apical membrane.
    [Abstract] [Full Text] [Related] [New Search]