Effects of electrical stimulatory cue on syncytial aGPVM cultures, specifically in regards to AP properties, Ca2+ transients, and β-adrenergic responsiveness. Format identical to that in Fig. 2. A: AP and Ca2+ properties, demonstrating slight AP plateau enhancement and phase 3 acceleration in exemplar APs (Ab). Ae: Small prolongation of APD80 evident in electrical restitution curve (*, p = 0.01). B: Amplified chronotropic responsiveness (*, p < 0.01). C: Renaissance of inotropic effects (*, p < 0.01).