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. I n whole-cell voltage-clamp experiments of rabbit parietal cells, A23187 (2 muM), a Ca2+ ionophore, activated the basolateral Cl- channels. The partial cDNA fragment of rabbit CLCA1 could be amplified from the total RNA of tra cheal epithelium, A Northern blot analysis showed that rabbit CLCA1 mRNA of 3.4 kb is highly expressed in the tracheal epithelium, but not in the gast ric 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. Thes e results suggest that the CLCA1 protein may not be a subunit of the housek eeping Ca2+-dependent Cl- channel in the basolateral membrane of rabbit gas tric parietal cells.