cDNA and non-reverse-transcribed RNA from confluent cultures of L/+, L/L, m/m and +/+ CCDs counterparts were amplified by RT-PCR. Each cDNA was amplified (30 cycles) with sets of specific primers for α-, β- and γ-ENaC, CFTR and β-actin, used as internal standard. +/+(L), +/+(m) and L/+ CCD cells yielded one band (260 bp) of β-ENaC amplified products. An additional band (370 bp), corresponding to the L allele, was also detected in cultured L/+ and L/L CCD cells. No amplified β-ENaC expression was detected in m/m CCD cells. As in the controls (C), no amplified products were detected when cDNA was omitted.