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Figure 4 Effect of Beta-Blockers on Anti-ß₁-Abs–Induced Receptor Activation

Beta-blockers do not fully abolish the Epac-FRET signals in cells stimulated with high-activator anti-ß₁-Abs. Neither the selective ß₁-AR anatagonists bisoprolol (Biso) (A) or metoprolol (Meto), nor nonselective drugs such as alprenolol (C) (Alpren) or carvedilol (Carved) blocked more than 70% of the FRET response induced by high-activator IgG under saturating conditions (3 µmol/l). Bisoprolol combined with EC_II peptides, however, could fully block high-activator-induced FRET signals (Biso + ECII) (D). (B) Concentration-response curve for the inhibitory effect of bisoprolol alone on high-activator-induced FRET signals. Data, means, and SEMs in (D) are calculated from at least 4 independent experiments. (E) The stimulatory effect of low-activator IgG could be fully abolished by bisoprolol. Representative experiments, n = 6. Quantification is shown in (F) together with the effect of a combination of bisoprolol with EC_I peptides (n = 5). Abbreviations as in Figures 1 and 2.

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