Mutations in the extracellular loop of α-rENaC alter sensitivity to amiloride and reactive species

Academic Article

Abstract

  • We studied the effects of two mutations of the extracellular loop of the α-subunit of the (ENaC) on amiloride-sensitive current in Xenopus laevis oocytes and the inhibition of this current by 3-morpholinosydnonimine (SIN-1). Injection of oocytes with wild-type (wt) α-,β-,γ-rENaC cRNA (8.3 ng/subunit) resulted 48-72 h later in inward Na currents (-5.5 ± 0.8 μA; means ± SE at -100 mV; n = 21), which were completely inhibited by amiloride. Oocytes injected with either α - or α - and β-,γ-rENaC cRNAs had significantly lower Na currents. Furthermore, α -,β-,γ-rENaC-injected oocytes had a higher K for amiloride (0.54 ± 0.97 vs. 0.10 ± 0.04 μM; P < 0.01). Exposure of oocytes to SIN-1 (1 mM) for 5 min decreased both total Na and amiloride-sensitive currents across wt and α - but not α -,β-,γ-rENaC. Furthermore, exposure to SIN-1 increased the K for amiloride across wt but not α -,β-,γ-rENaC-injected oocytes. These data indicate that both tyrosines are important for proper ENaC function and their oxidative modifications contribute to altered ENaC function. + + + Y279A Y283A Y279A i Y279A Y2S3A i Y279A
  • Digital Object Identifier (doi)

    Author List

  • Chen L; Fuller CM; Kleyman TR; Matalon S
  • Volume

  • 286
  • Issue

  • 6 55-6