Figure 4: Effect of β-blockers on expression of adenylyl cyclase and G protein subunits in the chick embryonic heart. Samples of myocardial membrane proteins prepared from ED9 chick embryos, both control (CON) and previously treated with metoprolol (Met) or carvedilol (Car) at ED4, ED8, or ED4 + ED8, were resolved by SDS-PAGE, transferred to nitrocellulose membranes, and probed with specific antibodies to AC5 isoform and α subunits of Gs and Gi(1,2) proteins. After stripping, the membranes were reprobed with actin antibody to control for differences in protein loading. Representative blots are shown, each of three independently performed experiments (a) and the graphical representation of relative expression levels (means ± SEM) of AC5, Gsα, and Giα normalized to the corresponding expression of actin (b). * Indicates a statistically significant difference between the indicated group affected by β-blockers and control ( ).