NCX1 is expressed in various tissues; therefore, future studies should determine whether our novel finding (i.e., a high- K+-induced Ca2+ influx via the NCX1 reverse-mode) is observable in other tissues, e.g., considering the high NCX1 expression in the heart [64], the involvement of NCX1 in high-K+-induced arrhythmia should be investigated. The gene discussed is SLC8A1; the disease is cardiac arrhythmia.