Ryanodine (Rya) pretreatment prevented BayK triggered SANC rate increases. A. Representative APs in control, in the presence of Rya and the combination of Rya plus BayK. B. SANC spontaneous pacemaking activity in the presence of Rya, the combination of Rya plus BayK, and BayK alone. *P<0.05 vs Rya and Rya+BayK, **P<0.001 vs Rya and Rya+BayK, #P<0.05 vs WT and AC3-C in the presence of BayK. n=7-10 cells from 3 animals for each genotypes.