The epithelial Na(+) channel (ENaC) is related to the hypertonicity-induced Na(+) conductance in rat hepatocytes.
The epithelial Na(+) channel (ENaC) is composed of the subunits alpha, beta, and gamma [Canessa et al., Nature 367 (1994) 463-467] and typically exhibits a high affinity to amiloride [Canessa et al., Nature 361 (1993) 467-470]. When expressed in Xenopus oocytes, conflicting results were reported concerning the osmo-sensitivity of the channel [Ji et al., Am. J. Physiol. 275 (1998) C1182-C1190; Hawayda and Subramanyam, J. Gen. Physiol. 112 (1998) 97-111; Rossier, J. Gen. Physiol. 112 (1998) 95-96]. Rat hepatocytes were the first system in which amiloride-sensitive sodium currents in response to hypertonic stress were reported [Wehner et al., J. Gen. Physiol. 105 (1995) 507-535; Wehner et al., Physiologist 40 (1997) A-4]. Moreover, all three ENaC subunits are expressed in these cells [Böhmer et al., Cell. Physiol. Biochem. 10 (2000) 187-194]. Here, we injected specific antisense oligonucleotides directed against alpha-rENaC into single rat hepatocytes in confluent primary culture and found an inhibition of hypertonicity-induced Na(+) currents by 70%. This is the first direct evidence for a role of the ENaC in cell volume regulation.
Böhmer
C
C
Max-Planck-Institut für molekulare Physiologie, Abteilung Epithelphysiologie, Otto-Hahn-Str. 11, 44227, Dortmund, Germany.
Wehner
F
F
D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D016373:DNA, Antisense; D004594:Electrophysiology; D053503:Epithelial Sodium Channels; D022781:Hepatocytes / Q000166:cytology; D006982:Hypertonic Solutions; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015222:Sodium Channels / Q000235:genetics / Q000502:physiology*; D014982:Xenopus laevis
D016373:DNA, Antisense; D053503:Epithelial Sodium Channels; D006982:Hypertonic Solutions; D015222:Sodium Channels