Characterization of <i>Bj</i>-PRO-10c-induced [Ca²⁺]<i>_i</i> elevations in endothelial cells.

<p><b>A.</b> Changes of maximal peak heights of [Ca²⁺]_i responses induced by increasing concentrations of <i>Bj</i>-PRO-10c (0.01–3 µM) were measured in HUVEC and HUVEC-PE by microfluorimetry. <b>B.</b> Evaluation of <i>Bj</i>-PRO-10c-induced [Ca²⁺]_i transients in HUVEC and HUVEC-PE in the presence of chelating agents and specific inhibitors of Ca²⁺ signaling. Cells were pre-incubated for 5 or 30 min with 10 mM EGTA or 10 µM BAPTA (extracellular and intracellular Ca²⁺ chelators), respectively. Cells also were pre-treated for 18 h with 100 ng/ml pertussis toxin (PTX) for inhibition of G_i/o-protein mediated receptor responses and for 30 min with U73122, a PLC-γ inhibitor. Calcium release from intracellular stores was inhibited by a 30 min pre-incubation of cells with 200 ng/ml thapsigargin. The participation of ryanodine-sensitive calcium stores was studied following 30 min pretreatment of cells with 50 µM ryanodine. * <i>P</i><0.05, ** <i>P</i><0.01 and *** <i>P</i><0.001 compared to <i>Bj</i>-PRO-10c control data obtained in the absence of pre-treatment. The shown data are mean values ± S.E. of five independent experiments.