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Active NaCl absorption across posterior gills of hyperosmoregulating Chasmagnathus granulatus

Onken, H. - Tresguerres, M. - Luquet, C.M.
Tipo de documento: 
Chasmagnathus granulatus - Crab gill - Crustacea - Flux measurement - Inhibitor - Ion substitution - Ion transport - Osmoregulation - Short-circuit current - Transepithelial conductance - Ussing chamber - acetazolamide - anthranilic acid derivative - fenamic acid - ouabain - sodium chloride - absorption - active transport - animal - article - Brachyura - comparative study - electrolyte balance - electrophysiology - gill - ion transport - metabolism - physiology - Absorption - Acetazolamide - Animals - Anthranilic Acids - Biological Transport, Active - Brachyura - Electrophysiology - Gills - Ion Transport - Ouabain - Sodium Chloride - Water-Electrolyte Balance - Animalia - Brachyura - Chasmagnathus granulata - Crustacea - Decapoda (Crustacea) - Strophanthus gratus
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.
J. Exp. Biol. 2003;206(6):1017-1023

Cita bibliográfica:

Onken, H. ; Tresguerres, M. ; Luquet, C.M.  (2003).  Active NaCl absorption across posterior gills of hyperosmoregulating Chasmagnathus granulatus.  (info:eu-repo/semantics/article).  [consultado:  ] Disponible en el Repositorio Digital Institucional de la Universidad de Buenos Aires:  <http://hdl.handle.net/20.500.12110/paper_00220949_v206_n6_p1017_Onken>