Figure 3. Effect of nifedipine on the increase in [Ca²⁺]_i elicited by high K⁺ in CGNs with or without GDF-15 treatment.

(A) Ca²⁺ imaging before and after depolarization by application of a 27-mM K⁺ solution in GDF-15-treated CGNs in the presence or absence of nifedipine. Scale bar, 50 μm. (B) Changes in [Ca²⁺]_i upon application of a depolarizing stimulus, as measured by quantification of fluorescence excitation ratios. Each arrow represents a 30-s perfusion with a depolarizing 27-mM K⁺ solution. (C) Statistical analysis of [Ca²⁺]_i in control and GDF-15-treated CGNs in the presence or absence of nifedipine. Results are means±S.E.M. *P<0.05 for the two groups connected with a straight line. Ctrl, control.