Study Set Content:
higher doses inhibit
both systemic
COX-1 and COX-2.
promote the uptake of two
molecules of oxygen by cyclization of arachidonic acid
Both COX-1 and COX-2
Both COX-1 and COX-2 promote the uptake of two
molecules of oxygen by cyclization of arachidonic acid to
yield a C 9 – C 11
endoperoxide
C 15
hydroperoxide
Both COX-1 and COX-2 promote the uptake of two
molecules of oxygen by cyclization of arachidonic acid to
yield a C 9 – C 11 endoperoxide C 15 hydroperoxide
This product is
PGG2
Both COX-1 and COX-2 promote the uptake of two
molecules of oxygen by cyclization of arachidonic acid to
yield a C 9 – C 11 endoperoxide C 15 hydroperoxide
This product is PGG2, which is then rapidly modified by
the peroxidase moiety of the COX enzyme to add a 15-
hydroxyl group that is essential for biologic activity. This
product is
PGF 2
2. Both endoperoxides are
highly unstable
PGH1 and PGH3 and all their subsequent products- are
derived from
homo-y-linolenic acid and eicosapentaenoic
acid, respectively.
The prostaglandins differ from each other in two ways:
In the substituents of the pentane ring
In the number of double bonds in the side chains
In the substituents of the pentane ring (indicated by
the
last letter
In the number of double bonds in the side chains
(indicated by the
subscript
PGH2 is metabolized by
prostacyclin,
thromboxane, and PGF synthases
PGH2 is metabolized by prostacyclin,
thromboxane, and PGF synthases (PGIS, TXAS,
PGFS) to
PGI 2, TXA 2, and PGF 2a,
TWO ADDITIONAL ENZYMES
9,11- endoperoxide reductase and
o 9-ketoductase
– provide for PGF 2a synthesis
from PGH2 and PGE2, respectively.
o 9-ketoductase, 9,11-endoperoxide reductase
At least three PGE2 synthases have been
identified:
o Microsomal (m) PGES-1
o The more readily inducible Mpges-2
o Cytosolic PGES.
There are two distinct Prostaglandin-D synthase
(PGDS isoforms)
o Lipocalin-type PGDS
o Hematopoietic PGDS
may be used for its smooth muscle
relaxing effects to maintain the ductus arteriosus patent
in some neonates awaiting cardiac surgery and in the
treatment of impotence.
Alpostadil (PGE1)
a PGE1 derivative, is a cytoprotective
prostaglandin used in preventing peptic ulcer and in
combination with mifepristone (RU-486) for terminating
early pregnancies.
Misoprostol
are used in obstetrics to induce labor.
PGE2 and PGF2
