Figure 1.

GTP[γS]-induced Ca²⁺ release in saponin-permeabilized platelets from normal subjects (○) and the patient (▴). Platelet suspensions were permeabilized with saponin (10–15 μg/ml) in the presence of 1 mM ATP, 1 μM CaCl₂, and 6 μM Quin2 acid. For measurement of Ca²⁺ concentrations, fluorescence was recorded (excitation, 339 nm; emission, 492 nm) using a Perkin–Elmer spectrofluorimeter and calculated as described in the text.