Active NaCl absorption across posterior gills of hyperosmoregulating Chasmagnathus granulatus

En:

J. Exp. Biol. 2003;206(6):1017-1023

Fecha:

2003

Formato:

application/pdf

Tipo de documento:

info:eu-repo/semantics/article
info:ar-repo/semantics/artículo
info:eu-repo/semantics/publishedVersion

Descriptores:

Chasmagnathus granulatus -  Crab gill -  Crustacea -  Flux measurement -  Inhibitor -  Ion substitution -  Ion transport -  Osmoregulation -  Short-circuit current

Descripción:

Split lamellae of posterior gills of Chasmagnathus granulatus adapted to 2.5‰ salinity were mounted in a modified Ussing chamber. With NaCl-saline on both sides of the preparation a transepithelial voltage (Vte) of 4.1±0.5 mV (outside positive) was measured. After voltage-clamping, the negative short-circuit current (Isc) amounted to -142±21 μA cm-2 at a conductance (Gte) of 44±5 mS cm-2. Substitution of either chloride (by nitrate) or sodium (by choline) on both sides of split gill lamellae significantly reduced Isc (by 70-80%) and Gte (by 30-50%). External CsCl (but not BaCl2 or furosemide) inhibited the negative Isc without affecting Gte. Addition of ouabain, BaCl2 or diphenylamine-2-carboxylate to the internal bath inhibited Isc at unchanged Gte. Internal acetazolamide did not affect Isc or Gte across split gill lamellae. Unidirectional Na+ influx across isolated and perfused posterior gills, however, was reduced by internal acetazolamide by approximately 20% at constant Vte. The results suggest that posterior gills of hyperosmoregulating C. granulatus display a high conductance epithelium that actively absorbs NaCl in a coupled way by an electrogenic mechanism similar to that seen in the thick ascending limb of Henle's loop and, to a minor degree, by an electroneutral mechanism, presumably via apical Na+/H+and Cl-/HCO3--antiports.
Fil:Tresguerres, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.
Fil:Luquet, C.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

Identificador(es):

http://hdl.handle.net/20.500.12110/paper_00220949_v206_n6_p1017_Onken

Derechos:

info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/2.5/ar