Abstract:

Objective To investigate the whole length and the splicing variants of the large conductance calcium activated potassium channels(BKCa) mRNA in mice colonic smooth muscle, and the semi-quantify at BKCa α-subunit in various segments of gastrointestinal tract.
Methods To observe the expression of BKCa α-subunit mRNA and protein in smooth muscle from various segments of gastrointestinal tract by RTPCR and Western blotting, and to examine the splice forms of all the splicing sites of BKCa mRNA in colonic smooth muscle by RT-PCR.
Results The expressions of BKCa both at the mRNA and the protein levels, in the smooth muscles of mouse stomach and colon were more abundant than those in duodenum and ileum. Exon 19(stress-regulated exon, STREX) was spliced in the mRNA of BKCa α subunit in colonic smooth muscle while no splicing on other exons was detected.
Conclusion The abundance of BKCa in colonic smooth muscle is high among the smooth muscles of the various gastrointestinal segments. The splicing variant BKCa in colonic smooth muscle was STREXlacking type, namely ZERO type.

Key words: smooth muscle, colon, large conductance calcium activated potassium channels, splicing variant, stress-regulated exon