Figure 4. Effects of NCX inhibitor 2′,4′-dichlorobenzamil on the nifedipine-resistant component of PE-mediated [Ca²⁺]_i oscillations and tonic contraction.

Blockade of Ca²⁺ entry through NCX with 100 μm 2′,4′-dichlorobenzamil (2,4-DCB) led to a large inhibition of PE-induced tonic contraction (A) and a complete inhibition of PE-induced [Ca²⁺]_i oscillations (B) in rings pretreated with 10 μm nifedipine. The remaining contraction was abolished by application of 50 μm SKF96365 (SKF) while the non-oscillating [Ca²⁺]_i was correspondingly reduced. (* Control refers to the amplitude of PE-mediated tonic contraction in rings pretreated with 10 μm nifedipine.)