title: Subunits alpha, beta and gamma of the epithelial Na+ channel (ENaC) are functionally related to the hypertonicity-induced cation channel (HICC) in rat hepatocytes.
abstract: Specific small interfering RNA (siRNA) constructs were used to test for the functional relation of subunits alpha, beta, and gamma of the epithelial Na(+) channel (ENaC) to the hypertonicity-induced cation channel (HICC) in confluent rat hepatocytes. In current-clamp recordings, hypertonic stress (300 --> 400 mosM) increased membrane conductance from 75.4 +/- 9.4 to 91.1 +/- 11.2 pS (p < 0.001). The effect was completely blocked by 100 microM amiloride and reduced to 46, 30, and 45% of the control value by anti-alpha-, anti-beta-, and anti-gamma-rENaC siRNA, respectively. Scanning acoustic microscopy revealed an initial shrinkage of cells from 6.98 +/- 0.45 to 6.03 +/- 0.43 pl within 2 min. This passive response was then followed by a regulatory volume increase (RVI) by 0.42 +/- 0.05 pl (p < 0.001). With anti-alpha-, anti-beta-, and anti-gamma-rENaC siRNA, the volume response was reduced to 31, 31, and 36% of the reference level, respectively. It is concluded that all three subunits of the ENaC are functionally related to RVI and HICC activation in rat hepatocytes.
authors.affiliation: Max-Planck-Institut für molekulare Physiologie, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Plettenberg
authors.forename: Eike C
authors.initials: EC
authors.lastname: Weiss
authors.forename: Robert
authors.initials: R
authors.lastname: Lemor
authors.forename: Frank
authors.initials: F
authors.lastname: Wehner
mesh_terms: D000465:Algorithms; D000818:Animals; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D004594:Electrophysiology; D053503:Epithelial Sodium Channels / Q000502:physiology*; D022781:Hepatocytes / Q000502:physiology*; D008839:Microelectrodes; D033401:Microscopy, Acoustic; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D053503:Epithelial Sodium Channels; D034741:RNA, Small Interfering