FIGURE 5.

Orai1-BK_Ca interaction and BK_Ca channel protein expression level alterations in diabetic mouse small intestinal smooth muscle cells and role of store-operated Ca²⁺ entry (SOCE) and the BK_Ca channel in carbachol (CCh)-induced mouse small intestinal longitudinal contraction. (A) Representative paired images and summarized data showing co-immunoprecipitation followed by immunoblotting (IB) with anti-BK_Ca channel or anti-Orai1. Proteins from small intestinal smooth muscle of age-matched control (CON) or diabetic (DM) mice were immunoprecipitated with anti-Orai1 antibody; n = 4 experiments. Representative images (B) and summarized data (C) showing the expression level of the BK_Ca channel protein. Alpha-actin was used as a loading control. Values are shown as the mean ± SEM (n = 4); P > 0.05, age-matched control vs. diabetic mice. Representative traces (D,E) and summarized data (E,G) showing 100 μM CCh-induced mouse small intestine contractions. The segments of the small intestine were pretreated with 50 nM IbTX for 20 min (D,E) or transfected with scrambled or Orai1 siRNA (F,G) by intraperitoneal injections. Values are shown as the mean ± SEM (n = 7–10); *P < 0.05, control (CON) vs. IbTX treatment, or scrambled siRNA vs. Orai1 siRNA.