Regulation of arachidonic acid release by enzyme(s) of rat brain cortex.
Brain cortex membranes labeled with [14C]arachidonic acid were used as the source of substrate and enzyme for the assay of arachidonic acid (AA) liberation. A significant amount of AA was released Ca2(+)-independently, mainly from phosphatidic acid, polyphosphoinositides and phosphatidylserine. Quinacrine, inhibitor of phospholipase A2 (PLA2), suppressed AA release by 60% and neomycin, inhibitor of phospholipase C (PLC) by about 30%. Both inhibitors applied together have an additive effect. Physiological calcium level elevated AA liberation by 50%, whereas 2 mM calcium enhanced this process by a further 30%. Carbachol, exclusively in the presence of calcium, activated AA release selectively from phosphatidylinositol and diglycerides. We suggest that Ca2(+)-independent PLA2 and PLC play an important role in AA liberation, and that physiological increments of calcium may have serious implications.
Samochocki
M
M
Department of Neurochemistry, Polish Academy of Sciences, Warszawa.
Strosznajder
J
J
D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D002122:Calcium Chloride / Q000494:pharmacology; D002250:Carbon Radioisotopes; D002540:Cerebral Cortex / Q000201:enzymology*; D004533:Egtazic Acid / Q000494:pharmacology; D007700:Kinetics; D009355:Neomycin / Q000494:pharmacology; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D054467:Phospholipases A2; D010743:Phospholipids / Q000378:metabolism*; D011796:Quinacrine / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
D001095:Arachidonic Acids; D002250:Carbon Radioisotopes; D010743:Phospholipids; D016718:Arachidonic Acid; D004533:Egtazic Acid; D010741:Phospholipases A; D054467:Phospholipases A2; D010738:Type C Phospholipases; D011796:Quinacrine; D009355:Neomycin; D002122:Calcium Chloride