Interleukin-1beta stimulates phospholipase A2 activity in adult rat ventricular myocytes.
We have examined whether interleukin (IL)-1beta modulates phospholipase A2 (PLA2) activity in ventricular myocytes. PLA2 activity was measured in isolated membrane and cytosol fractions with (16:0,[3H]18:1) plasmenylcholine and (16:0,[3H]18:1) phosphatidylcholine in the absence and presence of Ca2+. When measured in the absence of Ca2+ with plasmenylcholine, exposure to 5 ng/ml IL-1beta caused an increase in membrane-associated PLA2 activity for 10 min that returned to basal levels by 20 min. In the presence of Ca2+ with phosphatidylcholine, IL-1beta had no effect on membrane-associated PLA2 but decreased cytosolic PLA2 activity. Additionally, IL-1beta caused an increase in arachidonic acid release in 20 min. Pretreatment with E-6-(bromomethylene)tetrahydro-3-(1-naphthalenyl)-2H-pyran-2-one, a selective Ca2+-independent PLA2 inhibitor, blocked IL-1beta-induced increases in both PLA2 activity and arachidonic acid release. Exposure to IL-1 receptor antagonist (IL-1RA) alone had no effect on membrane-associated PLA2 activity. When incubated with IL-1beta, IL-1RA inhibited the IL-1beta-enhanced PLA2 activity. These results show that, via activation of its receptors, IL-1beta stimulates specifically membrane-associated Ca2+-independent plasmalogen-selective PLA2 in rat ventricular myocytes.
McHowat
J
J
Department of Pathology, University of Arkansas for Medical Sciences, Little Rock 72205, USA.
Liu
S
S
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D004789:Enzyme Activation; D006352:Heart Ventricles; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D008297:Male; D009206:Myocardium / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D051381:Rats; D017207:Rats, Sprague-Dawley; D017472:Receptors, Interleukin-1 / Q000502:physiology; D011994:Recombinant Proteins
D007375:Interleukin-1; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins; D016718:Arachidonic Acid; D010741:Phospholipases A; D054467:Phospholipases A2