Figure 4.

Reversal of platelet stress fibre formation and induction of actin nodule formation is dependent on PKA activation. Platelets (2 × 10⁷/ml) were spread on 100 μg/ml fibrinogen for 25 minutes in the presence or absence of PKA inhibitors; 500 μM RP-8-CPT-cAMP (RP) and 10 μM KT5720 (KT), before being washed with PBS. The platelets were then treated with tyrodes containing 10 nM PGI₂ or 1 μM forskolin with or without PKA inhibitors 500 μM RP-8-CPT-cAMP and 10 μM KT5720, for a further 10 minutes. The platelets were then fixed, stained with FITC-phalloidin and imaged. (a) The levels of cAMP were assessed in basal suspended platelets, control and 10 nM PGI₂ treated spread platelets. (b) Representative images of spread platelets under different experimental conditions. (c) The number of spread platelets containing stress fibres were identified for each condition in control and treated samples. (d) The number of spread platelets containing actin nodules were identified for each condition in control and treated samples. (e) The average surface area of the spread platelets was analysed for each condition in control and treated samples using Image J. The experiments are an average of n = 3. p < 0.05. Scale bar is 5 μm.