Fig. 6.

Compression force-dependent activation of integrin αII_bβ₃. a Schematics of ‘no switch’ BFP (top) and ‘switch’ dual BFP setup (bottom). In the ‘switch’ setup, the platelet is first subjected to 50 cycles with a FGN coated bead at a compressive force of 20 pN (step 1), and then switched to 50 cycles with bead coated with JON/A. b Mouse platelet adhesion frequencies with JON/A were determined under conditions of no switch, or switch at the indicated compressive forces (f_c = 10, 20 pN), or ADP stimulation (10 µM). c–e Non-DM and DM platelets from mice or humans were subjected to 100 BFP cycles at f_c = 20 pN using FGN (c, e) or vWF-A1 (d) beads. Adhesion frequency was analyzed for every 10 consecutive cycles and plotted over time (2.5 s/cycle). f Isolated mouse non-DM and DM platelets were loaded with calcium dyes Oregon Green BAPTA and Fura Red, reconstituted with RBCs from the same mouse, and perfused over FGN matrices at 600 s⁻¹. The calcium changes in individual adherent platelets were monitored and the number of adherent platelets displaying Ca²⁺ flux analysed. g Non-DM and DM mouse platelets were resuspended in Tyrode’s buffer containing 1 mM Ca²⁺ or 1 mM EGTA/Mg²⁺, subjected to 50 BFP cycles using FGN-beads at f_c = 20 pN, and adhesion frequency determined. All results are expressed as the mean ± s.e.m. of n = 3 mice and assessed by unpaired, two-tailed Student’s t-test, where *p < 0.5; **p < 0.01