7. Secretion of vWF

Secretion of vWF

  • Constitutive
    • dimer and small multimers (pro-vWF and mature wWF)
  • Stimulus-induced
    • release from WP bodies (large multimers, mostly mature vWF) induced by:
      • thrombin
      • histamine
      • fibrin
      • C5b-9 (complement membrane attack complex)
      • O2 radicals
    • release from platelets (vWF stored in a-granules) after:
      • thrombin
      • ADP
      • Collagen

vWF function

  • In plasma, the predominant MW is b/w 500,000-20,000,000
  • The bigger the multimer:
    • more platelet and collagen binding sites
    • more hemostatically competent