FIG. 1.

Sequential stimulation of PMN by fPR1 (high-affinity)-saturating doses (10⁻⁷ M) of fMLP 5 min apart. (a) Control; (b) 5 mM EGTA added 15 s before the first fMLP injection; (c) 5 mM EGTA added before the second fMLP injection; (d) release of elastase (shown as F₄₆₀) and of oxidative products (shown as F₅₃₀). Each figure is representative of six independent experiments. In this and each of the following figures, the [Ca²⁺]_i and pH_i are indicated on the ordinates; F₄₆₀ is proportional to the elastase release, and F₅₃₀ is proportional to the release of oxidative products.