Figure 2. Changes in[Ca²⁺]_i, tension and MLC₂₀ phosphorylation due to PGF_2α under normal conditions or conditions where an increase in [Ca2+]_i was inhibited.

A, examples of changes in[Ca²⁺]_i in normal physiological saline solution (PSS), in the presence of verapamil (10 µm) or EGTA (4 mm). For[Ca²⁺]_i and tension, 100 % represents the change induced by 65.4 mm KCl, which was obtained before the application of PGF_2α. Verapamil or EGTA was applied 10 min before the addition of PGF_2α (10 µm). B, summarized data of the PGF_2α-induced contraction and MLC₂₀ phosphorylation in the normal medium or in the presence of verapamil and fasudil or hydroxyfasudil (OH-fasudil). Developed tension is expressed as a percentage of the maximum contraction to 65.4 mm KCl. C, summarized data of the PGF_2α-induced contraction and MLC₂₀ phosphorylation in the normal medium or in the presence of EGTA and fasudil or OH-fasudil. In B and C, MLC₂₀ phosphorylation (MLC-P) was measured at 5 min after the addition of PGF_2α (10 µm). When used, fasudil (10 µm) or hydroxyfasudil (OH-fasudil, 10 µm) was added 30 min before PGF_2α. The protocol in B and C was the same as that shown in A, but the experiments were performed in a different series. MLC₂₀ phosphorylation under the resting condition in normal PSS was 8.9 ± 2.4 % (data not shown). Verap: verapamil.