CORE FOUNDATIONS FOR MEDICINE TUTORIAL ON EICOSANOIDS

Thromboxane Stimulates Vasoconstriction

I. Platelets produce Thromboxane (TXA)       II. TXA stimulates vasoconstriction
  • Factors that stimulate clotting activate receptors on platelets
  • Phospholipase A2 is activated
  • PGH produced by COX-1 is converted to TXA
     
     
     
  • TXA diffuses a short distance to neighboring smooth muscle cells
  • TXA binds to the thromboxane receptor (TP), a Gq-linked G-protein coupled receptor
  • Ca2+ concentration increases
  • Ca2+ causes phosphorylation of myosin light chain
  • Vasoconstriction results

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