[THE EFFECTS OF LYS-PLASMINOGEN ON HUMAN PLATELET SECRETION].

Area of Science:

• Hematology
• Biochemistry
• Cell Biology

Background:

• Platelet activation is crucial for hemostasis and thrombosis.
• Alpha-granule secretion is a key platelet response involved in aggregation and inflammation.
• Plasminogen, particularly its Lys-form, has been implicated in various physiological processes.

Purpose of the Study:

• To investigate the effect of Lys-plasminogen on platelet alpha-granule secretion.
• To determine if Lys-plasminogen modulates platelet exocytosis.
• To explore potential mechanisms behind Lys-plasminogen's influence on platelet function.

Main Methods:

• Washed human platelets were used to study alpha-granule secretion.
• Flow cytometry was employed to measure P-selectin expression as a marker of alpha-granule release.
• Lys-plasminogen and Glu-plasminogen were tested for their effects on platelet secretion.

Main Results:

• Lys-plasminogen induced partial release of platelet alpha-granules.
• Lys-plasminogen inhibited thrombin-stimulated platelet exocytosis.
• Native Glu-plasminogen did not affect alpha-granule secretion.
• The effects are suggested to be mediated by kringle domains interacting with membrane receptors, not plasmin activity.

Conclusions:

• Lys-plasminogen modulates platelet alpha-granule secretion, distinct from Glu-plasminogen.
• This modulation involves both partial granule release and inhibition of thrombin-induced exocytosis.
• Lys-plasminogen's impact on platelet secretion is a potential mechanism for its anti-aggregating activity.