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Electrophysiology of posterior, NaCl-absorbing gills of Chasmagnathus granulatus: rapid responses to osmotic variations.
- Source :
-
The Journal of experimental biology [J Exp Biol] 2003 Feb; Vol. 206 (Pt 3), pp. 619-26. - Publication Year :
- 2003
-
Abstract
- In the present study, the influence of short-term osmotic variations on some electrophysiological properties related to NaCl absorption across posterior gills of Chasmagnathus granulatus was investigated. The transepithelial potential difference (V(te)) of isolated and perfused gills increased significantly when hyposmotic saline (699 mosmol l(-1)) was used instead of isosmotic solution (1045 mosmol l(-1)). A reduction of the concentration of Na(+) or Cl(-) at constant osmolarity did not produce any change in V(te). Transepithelial short-circuit current (I(sc)) and conductance (G(te)), measured with split gill lamellae mounted in a modified Ussing chamber, also increased after changing to hyposmotic salines (I(sc): from -89.0+/-40.8 microA cm(-2) to -179.3+/-37.0 microA cm(-2); G(te): from 40.5+/-16.9 mS cm(-2) to 47.3+/-15.8 mS cm(-2)). The observed effects of reduced osmolarity were fast, reversible and gradually dependent on the magnitude of the osmotic variation. The activity of the Na(+)/K(+)-ATPase increased significantly after perfusion with hyposmotic saline, from 18.73+/-6.35 micromol P(i) h(-1) mg(-1) to 41.84+/-14.54 micromol P(i) h(-1) mg(-1). Theophylline maintained part of the elevated V(te) induced by hyposmotic saline, suggesting that an increased cellular cyclic AMP level is involved in the response to reduced osmolarity. In summary, the results indicate that the hemolymph osmolarity regulates active transbranchial NaCl absorption by modulating the activity of the basolateral Na(+)/K(+)-ATPase and by changing a conductive pathway, probably at the apical membrane.
- Subjects :
- Animals
Brachyura drug effects
Cyclic AMP metabolism
Electrophysiology methods
Gills drug effects
Gills metabolism
Male
Membrane Potentials drug effects
Membrane Potentials physiology
Osmotic Pressure
Sodium-Potassium-Exchanging ATPase metabolism
Brachyura physiology
Gills physiology
Sodium Chloride pharmacology
Subjects
Details
- Language :
- English
- ISSN :
- 0022-0949
- Volume :
- 206
- Issue :
- Pt 3
- Database :
- MEDLINE
- Journal :
- The Journal of experimental biology
- Publication Type :
- Academic Journal
- Accession number :
- 12502782
- Full Text :
- https://doi.org/10.1242/jeb.00125