A, representative mRNA expression pattern of the β1-E transgene for two founder lines (R9 and R13) and wild-type controls (WT) measured by real-time PCR. No RT, negative control without reverse transcription. HT, heart; AO, aorta; LU, lung; SP, spleen; KI, kidney; BL, bladder; LI, liver; BR, brain; SK, skeletal muscle. Total RNA was prepared from organs and used as template for real-time PCR as described in the Methods. B, β1-E mRNA compared to endogenous BKβ1 mRNA expression strength by quantitative real-time PCR. Both transcripts were amplified from the same samples. Samples were AO, KI, BL and colon from three BKβ1+/+ β1-E transgenic mice of founder line R9. C, β1-E protein expression in bladder of BKβ1 R9 and BKβ1 R13 mice. Detection was by densitometry of chemoluminescence on anti-GFP Western blots normalized to anti-β-actin signals. n, number of animals. R9, BKβ1−/− β1-E mice (founder 9); R13, BKβ1−/− β1-E mice (founder 13); n.s., difference not statistically significant. Welch's paired t test was used for B and Mann–Whitney U test was used for C.