Prostacyclin (PGI2 )
Discussion
a. functions of Prostaglandin E2 (PGE2)
- Reduce gastric acid secretion
- Increase Gastric mucus secretion
- Contraction of uterus
- Contraction of GI tract smooth muscle
- Inhibit lipolysis
- Increase autonomic neurotransmitters
b. Prostaglandin (PGE2α )
- Contraction of uterus
- Bronchoconstriction
c. Functions of Thromboxane A2 (TXA2)
- Vasoconstriction
- Platelet aggregation
d. Functions of Prostaglandin D2 (PGD2)
- Bronchoconstriction
- Vasodilatation
e. Prostacyclin (PGI2 )
- Opposite effects of Thromboxane A2
Factors that cause vasoconstriction
Local factors
- Decreased local temperature
- Autoregulation
Endothelial products
- Endothelin-1
- Locally released platelet serotonin
- Thromboxane A2
Circulating hormones
- Epinephrine (except in skeletal muscle and liver)
- Norepinephrine
- AVP
- Angiotensin II
- Circulating Na+-K+ ATPase inhibitor
- Neuropeptide Y
Neural factors
- Increased discharge of sympathetic nerves
Factors that cause vasodilation
Local factors
- Increased CO2 and decreased O2
- Increased K+, adenosine, lactate, etc
- Decreased local pH
- Increased local temperature
Endothelial products
Circulating hormones
- Epinephrine in skeletal muscle and liver
- CGRP
- Substance P
- Angiotensin II
- Histamine
- ANP
- VIP
Neural factors
- Decreased discharge of sympathetic nerves
- Activation of sympathetic cholinergic vasodilator nerves to skeletal muscle
Reference
1.Ganong's review of medical physiology 23rd edition