Down regulated expression of the β1 subunit of the big-conductance Ca2+ sensitive K+ channel in sphincter of oddi cells from rabbits fed with a high cholesterol diet

Hypercholesterolemia, which is closely related to gallbladder bile stasis, can cause sphincter of Oddi dysfunction (SOD) by increasing the tension of sphincter of Oddi (SO). Intracellular calcium ion concentration ([Ca2+](i)) could influence the tension of SO. The beta 1 subunit of the big-conductance Ca2+ sensitive K+ channel (BKCa) can enhance the sensitivity of the BKCa channel to [Ca2+](i). Absence and decline of the BKCa channel subunit beta 1 could lead to many diseases. However, the relationship between hypercholesterolemia and the expression of beta 1 subunit is not well understood. In this study, we successfully expressed and purified the rabbit BKCa beta 1 subunit protein and prepared its polyclonal antibody. The specificity of the prepared antibody was determined by western blotting. A SOD rabbit model induced by a high cholesterol diet was established and the expression of the beta 1 subunit of SO was determined by immunohistochemical staining and western blotting. Compared with the controls, our results demonstrated that hypercholesterolemia could decrease the expression of the beta 1 subunit in the SO cells from rabbits. This indicates that lower expression of BKCa channel beta 1 subunit might induce SOD.