Expression of calcium channel TRPV6 in ovine epithelial tissue.

Functional studies indicate marked differences in the extent and site of gastrointestinal calcium absorption between monogastric and ruminant species. Given that the epithelial calcium channel TRPV6 has a pivotal role in active intestinal calcium transport, this study investigated TRPV6 expression in ovine duodenal, jejunal, ruminal and renal epithelial cells using RT-PCR, in situ hybridisation, Western blot analysis and immunohistochemistry. The expression patterns suggested that, in contrast to monogastric animals, the jejunum is more important than the duodenum for calcium absorption in sheep. Furthermore, the expression of TRPV6-specific transcripts in ruminal epithelium was much lower than expected and its sub-cellular localisation suggested that this ion channel does not contribute to calcium absorption from the forestomachs.