Ovine myometrial cytosol inhibits phospholipase A activity, in vitro.
Myometrium obtained from pregnant ewes (30-80 days gestation) contains a factor which inhibits phospholipase A2 (PLA2) activity. The activity of this moiety was assessed using an in vitro porcine pancreatic PLA2 assay system. Inhibitory activity was associated with a 35-45000 dalton molecular weight fraction, heat-labile, sensitive to protease degradation and did not partition into organic solvents. These data are indicative that PLA2-inhibitory activity resides in a protein moiety. Dixon-plot analysis of myometrial-inhibitory activity was indicative that the inhibition of PLA2 activity was of a non-competitive nature (Ki = 4.1 +/- 0.7 micrograms/ml, ca 118 nmol/l). Myometrial phospholipase-inhibitory protein(s) may be involved in the suppression of eicosanoid biosynthesis by the uterine tissues throughout gestation thus inhibiting uterine contractile activity.
Department of Physiology, Monash University, Clayton, Victoria, Australia.
G E
GE
Rice
M H
MH
Wong
G D
GD
Thorburn
D000818:Animals; D002855:Chromatography, Thin Layer; D003600:Cytosol / Q000378:metabolism*; D005260:Female; D066298:In Vitro Techniques; D009215:Myometrium / Q000378:metabolism*; D010740:Phospholipases / Q000037:antagonists & inhibitors*; D010741:Phospholipases A / Q000037:antagonists & inhibitors*; D054467:Phospholipases A2; D011247:Pregnancy; D012756:Sheep
D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2