Abstract
1. The expression of ClC-3 was examined in rat lacrimal gland and submandibular salivary gland cells using RT-PCR and Western analysis. Whole-cell patch clamp methods were used to investigate the expression of volume-sensitive anion channels in acinar cells isolated from these tissues. 2. Expression of mRNA encoding ClC-3, and ClC-3 protein, was found in rat submandibular gland by RT-PCR and Western analysis. Rat lacrimal gland cells, however, did not appear to express mRNA encoding for ClC-3, nor the ClC-3 protein. 3. Volume-sensitive anion conductances were observed in both rat lacrimal gland and submandibular salivary gland acinar cells. The conductance was of a similar size in the two cell types, but was much slower to activate in the lacrimal cells. 4. The properties of the conductances in lacrimal and submandibular cells were similar, e.g. halide selectivity sequence (P(I) > P(Cl) > P(aspartate)) and inhibition by 4,4'-diisothiocyanostilbene-2,2'-disulphonic acid, 5-nitro-2-(3-phenylpropylamino)-benzoate and tamoxifen. 5. The data suggest that the expression of ClC-3 is not an absolute requirement for the activity of volume-sensitive anion channels in rat lacrimal gland acinar cells.