Is rabbit CLCA1 related to the basolateral Ca²⁺-dependent Cl^- channel of gastric parietal cells?

An expression of mRNA coding the calcium-activated Cl^- channel-1 (CLCA1) in rabbit gastric parietal cells was examined to verify the possibility that the CLCA1 mediates housekeeping Cl^- channels in the basolateral membrane. In whole-cell voltage-clamp experiments of rabbit parietal cells, A23187 (2 μM), a Ca²⁺ ionophore, activated the basolateral Cl^- channels. The partial cDNA fragment of rabbit CLCA1 could be amplified from the total RNA of tracheal epithelium. A Northern blot analysis showed that rabbit CLCA1 mRNA of 3.4kb is highly expressed in the tracheal epithelium, but not in the gastric parietal cells. Even in a more sensitive detection of rabbit CLCA1 mRNA by RT-PCR, no signal could be observed in the gastric parietal cells. These results suggest that the CLCA1 protein may not be a subunit of the housekeeping Ca²⁺-dependent Cl^- channel in the basolateral membrane of rabbit gastric parietal cells.