Fig 2. The chronotropic response to isoproterenol on spontaneous beat rate of healthy (black symbols), IsP (red symbols) and AuP (blue symbols) EBs.

Panel [A] shows representative spontaneous electrogram recordings from healthy (left), IsP (middle) and AuP (right) EBs in the absence (upper) and presence (middle) of isoproterenol. The positive chronotropic effect of isoproterenol is blocked by the β-blocker metoprolol (lower). [B] The spontaneous beating rate of healthy (clone 24.5 n = 6, clone KTN3 n = 5, clone KTI n = 7, n = 18), IsP (clone 23.10 n = 5) and AuP (n = 3) EBs. [C] Summary of the response to isoproterenol of healthy (black), IsP (red) and AuP (blue) EBs. Results are expressed as Mean±SEM. There is no statistically significant difference between the groups in Two-way ANOVA test. Iso–isoproterenol, MP–metoprolol.