Figure 6. The α1A- and α1B-Subytpes Form Hetero-oligomers that Influence α1-AR Signaling in Adult Cardiac Myocytes.

(A) Representative confocal images of a nucleus from an α1ABKO cardiac myocyte expressing both the α1B-CFP (upper left) and α1A-GFP (lower left). The resulting raw FRET image (top center) and sensitized FRET image corrected for crosstalk between CFP and GFP emission (bottom center). FRET efficiency between α1B-CFP and α1A-GFP in the nucleus (upper right) and calculated FRET distances between α1B-CFP and α1A-GFP (bottom right) indicating hetero-oligomerization (n=3 separate cultures). The brightness of the fluorescent images was enhanced to aid visualization of color against the black background. (B) Representative Western blot for P-ERK and T-ERK in wild-type cardiac myocytes treated with 20 µM PE. (C) Representative Western blots for P-ERK and T-ERK in α1AKO cardiac myocytes infected with adenovirus expressing the α1A- alone (lane 2), the α1B- alone (lane 3) or both (lane 4) and treated with 20 µM PE. (D) Representative Western blots for P-ERK and T-ERK in α1BKO cardiac myocytes infected with adenovirus expressing the α1A- alone (lane 2), the α1B- alone (lane 3) or both (lane 4) and treated with 20 µM PE. Semi-quantitative analysis of Western Blots shown are shown in B, C and D. Replicate experiments (n=3 separate cultures) were quantified by densitometry and treatments were compared by ANOVA with a Bonferonni post-test. NS = not significant.