Figure 3. Effect of PMA on Ca²⁺ and Sr²⁺ entry in human platelets.

A and B, platelets were treated with 1 μm PMA in HBS containing 1 mm Ca²⁺ (A) or 1 mm Sr²⁺ (B; n = 6). The same experiments were performed in the absence of external Ca²⁺ (A) or Sr²⁺ (B; n = 6). C and D, cells were treated with TG (200 nM) in Ca²⁺-free HBS (100 μm EGTA added) and 3 min later SrCl₂ (final concentration, 300 μm) was added followed by PMA (1 μm, D) or the vehicle (DMSO) alone (C; n = 6).