Mobilization of
arachidonic acid from
glycerophospholipids and
prostaglandin (PG) release from fetal membranes were studied in women with dysfunctional labor in the absence of
cephalopelvic disproportion or fetal malposition. Using superfusion of intact amnion and chorion, we found a slight decrease in
PGE and a more significant decrease in
PGF release by the amniotic side of the fetal membrane obtained from women with dysfunctional labor compared to that in women with normal labor (
PGE: normal labor, 2992 pg/cm2.h; dysfunctional labor, 1846 pg/cm2.h; P less than 0.05;
PGF: normal labor, 662 pg/cm2.h; dysfunctional labor, 204 pg/cm2.h; P less than 0.02). Release of both
prostanoids was significantly greater from the amniotic side in tissues obtained after labor compared to that in prelabor tissue. Analysis of
arachidonic acid (by gas liquid chromatography) and
phospholipid content (by two-dimensional thin layer chromatography) confirmed metabolic disposal of
arachidonic acid from the amnion after the onset of labor. However, no difference in either
phospholipid or
phospholipase A2-releasable
arachidonic acid of individual
phospholipid classes was found in amnion tissue from women with normal and dysfunctional labor, suggesting similar activities of
phospholipase A2 in these two groups. The finding of decreased free and
phospholipase A2-releasable
arachidonic acid of the total
lipid extract of the amnion of women with dysfunctional labor could suggest further metabolic exhaustion of the substrate or failure of liberation of this
fatty acid from
glycerophospholipids by
enzymes other than
phospholipase A2, such as
phospholipase C or diacyl and monoacylglycerolipases.