
Fig. 5. Effects of extracellular Ca2+ on atrial beating. (A) Representative control response after treatment with synthetic EI-14 in normal Ringers solution. EI-14 (10-7moll-1) was applied during the period indicated by the horizontal bar. (B) Effects of EI-14 in the absence of Ca2+ in the bathing medium. Ca2+ was omitted during the period indicated by the horizontal bar (Ca2+-free). (C) Effects of EI-14 after pretreatment with verapamil. Verapamil (10-5moll-1) was applied during the period indicated by the horizontal bar.