Figure 4.

Ca²⁺ is required for PASMC contraction and PASMC proliferation. (a) Extracellular Ca²⁺ is required for pulmonary vasoconstriction induced by 40 mM K⁺ (40 K) and phenylephrine (PE). Ca²⁺-free solution was applied to the vessels when 40 mM K⁺- or PE-mediated contraction reached a plateau. Data showing active tension induced by 40 mM K⁺ or 2 μM PE before (control), during (0 Ca), and after (recovery) application of Ca²⁺-free solution [25]. (b) Inhibition of rat PASMC growth by chelating extracellular Ca²⁺. Cells were cultured in 10% FBS-DMEM in the absence (Cont) and presence of 2 mM EGTA. Viable cell numbers were determined 1, 4, and 6 days after cells were plated. Data are means ± SE (n = 12 dishes of cells/group). **P < 0.01, ***P < 0.001 versus control [31].