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Activities of Phospholipase A2, Cyclooxygenase, and PGI2 Synthase of Umbilical Venous Endothelial Cells in Preeclamptic Women
Author(s) -
Seki Hiroyuki,
Takeda Satoru,
Kinoshita Katsuyuki,
Satoh Kazuo
Publication year - 1994
Publication title -
asia‐oceania journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 50
eISSN - 1447-0756
pISSN - 0389-2328
DOI - 10.1111/j.1447-0756.1994.tb00491.x
Subject(s) - cyclooxygenase , arachidonic acid , medicine , prostacyclin , endocrinology , phospholipase a2 , preeclampsia , chemistry , atp synthase , pregnancy , enzyme , biology , biochemistry , genetics
To elucidate the cause of low prostacyclin (PGI 2 ) production in severe preeclampsia (PE), we studied the activities of phospholipase A 2 , cyclooxygenase, and PGI2 synthase in umbilical venous endothelial cells obtained from healthy pregnant women and from patients with mild or severe PE. Umbilical venous endothelial cells homogenized in a buffer solution were analysed by calculating the apparent V max (mean ± SEM: p mol/min mg protein) and K m (mean ± SEM:;μm) values for phospholipase A 2 activity by the release of arachidonic acid from phosphatidylcholine, for the activity of a complex of cyclooxygenase and PGI2 synthase by the conversion of arachidonic acid to PGI 2 , and the activity of PGI 2 synthase by conversion of PGH2 to PGI2. The phospholipase A 2 activity of normal‐pregnancy cells ( V max ; 17.0 ± 2.7 K m : 0.26 ± 0.04) ( n = 10) significantly exceeded that of cells from women with either mild PE (5.8 ±0.5, 0.12 ± 0.02) ( n = 4) or severe PE (6.3 ±2.0, 0.08 ± 0.03) ( n = 5). The apparent combined activity of cyclooxygenase and PGI 2 synthase in mild PE (552 ± 142, 0.29 ± 0.07) ( n = 8) significantly exceeded that of a normal pregnancy (176 ± 42, 0.76 ± 0.25) ( n = 7), whereas that in severe PE (326 ± 36, 3.26 ±0.78) ( n = 3) was significantly lower than that of a normal pregnancy. PGI2 synthase activity in mild PE (305 ± 50, 0.12 ± 0.07) ( n = 4) exceeded that of a normal pregnancy (220 ±45, 0.13 ±0.06) ( n =5), whereas that in severe PE (55 ±12, 0.16 ± 0.04) ( n = 3) was lower than that of a normal pregnancy. The phospholipase A2 activity in cells of normal pregnant women exceeded that of cells of women with mild or severe PE. The combined activity of cyclooxygenase and PGI 2 synthase in a normal pregnancy was lower than in mild PE, but higher than in severe PE. Similar results were found for PGI 2 synthase activity; in normal pregnancy the activity was less than in mild PE, but higher than in severe PE. Low production of PGI 2 in severe PE seems to result from a decreased activity of enzymes that produce PGI 2 , especially cyclooxygenase.