Expression patterns and potential action of the calcium transport genes Trpv5, Trpv6, Ncx1 and Pmca1b in the canine duodenum, kidney and uterus.

Four membrane calcium (Ca²⁺) channels are known to play an important role in calcium transport: transient receptor potential cation channel subfamily V members 5 and 6 (Trpv5/6), Na⁺/Ca²⁺ exchanger 1 (Ncx1) and plasma membrane Ca²⁺-transporting ATPase1 (Pmca1b). These channels have been shown to mediate the transport of Ca²⁺ between the cytosol and bloodstream in multiple tissues, including the duodenum, kidney, and uterus. Trpv5 and Trpv6 are known to selectively import Ca²⁺ into cells, while Ncx1 and Pmca1b function to extrude Ca²⁺. The present study examined and compared expression patterns of these genes in the canine duodenum, kidney and uterus. We confirmed expression of all four genes in this canine model. To collect tissues for analysis, two adult (2.5-year-old) female dogs were euthanized and tissue samples were collected from an abdominal incision. Expression of Trpv5/6, Ncx1 and Pmca1b was analyzed by reverse transcription polymerase chain reaction (RT-PCR), Western blot analysis, and immunohistochemistry. Trpv5, Trpv6 and Ncx1 mRNA were highly expressed in the kidney, while Pmca1b mRNA was primarily detected in the uterus. Protein expression was verified by Western blot analysis and localized by immunohistochemistry. Protein expression showed patterns similar to those of mRNA expression. Taken together, these results indicate that transcriptional and transitional expression of Tprv5, Trpv6, Ncx1 and Pmca1b may play a critical role in calcium transport in the canine duodenum, kidney and uterus.