8.5.1.2 Prostaglandins: Pharmacological Effects
The pharmacological effects of the prostaglandins and TXA 2 comprise many different
activities—in fact too many. The lack of specificity of their activities implies a number of
side effects which preclude the clinical application of several highly active natural
prostaglandins, necessitating the development of selective synthetic compounds. The following effects of prostaglandins/eicosanoids are known and are summarized in table 8.3.
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Table 8.3 Biologic Activities Associated with the Eicosanoids
Substance
Observed biologic Activity
PGD 2
Weak inhibitor of platelet aggregation
PGE 1
Bronchodilatation
Inhibitor of fat breakdown
Inhibitor of platelet aggregation
Stimulates contraction of gastrointestinal smooth muscle
Vasodilation
PGE 2
Elevates body temperature set-point in anterior hypothalamus
Protects stomach lining acid degradation
Reduces secretion of stomach acid
Renal vasodilatation in kidneys
Stimulates uterine smooth-muscle contraction
PGF 2
Stimulates uterine smooth-muscle contraction
PGl 2
Potent inhibitor of platelet aggregation
Potent vasodilator
PGJ 2
Inhibits cell proliferation
Stimulates osteogenesis (bone formation)
TXA 2
Potent inducer of platelet aggregation
Potent vasoconstrictor
Stimulates release of serotonin from platelets
LTB 4
Increases leukocyte chemotaxis and aggregation
LTC/D 4
Bronchoconstrictive
5- or 12-HPETE
Inhibits platelet aggregation
Aggregates leukocytes
Promotes leukocyte chemotaxis