ASM cells from rat express multiple isoforms of RYRs (Du et al., 2005). As a first step to address the spatial relationship between BK channels and RYRs, we identified the RYR isoforms in ASM from mice. Using primers specific for each isoform of RYR, all three of RYR mRNA from de-epithelial tracheal tissues (Fig. 4 A) were detected by reverse transcription PCR. It appears there is only a small amount of mRNA for RYR3 in these cells. The lower abundance of this isoform of RYR cannot be attributed to the primer specificity because RYR3 was readily detected in hippocampus from the same mouse (Fig. 4 A).
