KCNMA1 and Sinus bradycardia: In the context of SAN function, it has also been shown that knock down of the large-conductance Ca2+-activated K+ channel (KCa1.1) in zebrafish, which is strongly expressed in the human SAN, results in sinus bradycardia (Pineda et al., 2021), so it may play an important role in zebrafish SAN automaticity through its contribution to repolarisation.