CHANGES IN PHOSPHOLIPASE-A2 IN MYOMETRIUM OF THE GUINEA-PIG UTERUS DURING PREGNANCY

被引:0
作者
KHOUJA, A
JONES, CT
机构
[1] UNIV OXFORD, JOHN RADCLIFFE HOSP, INST MOLEC MED, CELLULAR & DEV PHYSIOL LAB, OXFORD OX3 9DU, ENGLAND
[2] UNIV OXFORD, JOHN RADCLIFFE HOSP, NUFFIELD DEPT CLIN MED, OXFORD OX3 9DU, ENGLAND
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Q [生物科学];
学科分类号
07 ; 0710 ; 09 ;
摘要
Phospholipase A2 activity has been measured in membrane and cytosolic fractions from non-pregnant and pregnant guinea pig myometrium has been studied. Enzyme activity was measured with 1-stearoyl-2-[H-3]arachidonoyl-phosphatidylcholine exhibiting Michaelis-Menton kinetics with K(m) of 83.8 +/- 21.6 and 53.2 +/- 14.1 for membrane and cytosolic enzymes respectively. Fractionation of the myometrium from non-pregnant guinea pigs suggested that 35% of the activity was membrane associated compared with 20% (P<0.01) in tissue from pregnant animals. In the presence of 1 mM calcium total activity rose from 3.03 +/- 0.41 to 1737 +/- 368 nmol/h per uterus between non-pregnant and late pregnancy. Calcium activated the membrane enzyme, but the effect was greater late in pregnancy with almost a 6-fold increase in activity at 1 mM calcium compared with a doubling in membrane from non-pregnant guinea pigs. The K0.5 for calcium activation was about 150 muM. Immunoblotting with anti-human-110 KDa phospholipase A2 showed in guinea pig uterus a 34 KDa form of the enzyme that, consistent with changes in activity, showed a fifteen-fold increase in quantity between non-pregnant and late pregnancy. The data are consistent with dramatic increases in the capacity for arachidonic acid release and prostaglandin production in the guinea pig myometrium late in pregnancy.
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页码:271 / 277
页数:7
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