抄録
We examined the expression of Na/K-ATPase α-subunit isoforms in salivary glands by RT-PCR. mRNA of α1 isoform was abundant in all 3 major salivary glands. The α2 isoform was expressed in submandibular gland (SMG) and sublingual gland (SLG), and faintly in the parotid gland (PG). In contrast, α3 was expressed in the SLG alone. The α3 mRNA was also detected in dispersed cells that had been prepared from the SLG to remove nerve termini. The Na/K-ATPase α3 protein was detected in the membrane preparation from SLG with anti-α3 isoform monoclonal antibody by Western blot analysis. These results indicate that SLG actually expressed the α3 isoform. Furthermore, we also found the presence of antisense RNA of Na/K-ATPase α3 isoforms in rat SLG by conducting RT-PCR with gene-specific forward primers. The first strand cDNA was synthesized with specific forward primers targeted to the CDS region or the promoter region of upstream from the transcription start site. PCRs with these 1st-strand cDNAs revealed the reasonable PCR products of Na/K-ATPase α3 isoform. The antisense RNA was disrupted by treatment of the total RNA preparations with RNase prior to synthesis of 1st strand cDNAs. These results suggest the presence of antisense RNA of Na/K-ATPase α3 isoform in rat SLG. The level of the sense RNA of α3 isoform was higher than that of antisense RNA of the enzyme. The α3 antisense RNA as well as the α3 sense RNA was abundant in SLGs of female rats. [J Physiol Sci. 2007;57 Suppl:S134]
