is required for PASMC contraction and PASMC proliferation. (a) Extracellular is required for pulmonary vasoconstriction induced by 40 mM (40 K) and phenylephrine (PE). -free solution was applied to the vessels when 40 mM - or PE-mediated contraction reached a plateau. Data showing active tension induced by 40 mM or 2 M PE before (control), during (0 Ca), and after (recovery) application of -free solution [25]. (b) Inhibition of rat PASMC growth by chelating extracellular . 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 ( dishes of cells/group). **, *** versus control [31].