Gamma-thrombin-induced phospholipase A2 activation in rabbit platelets: comparison with alpha-thrombin.
gamma-Thrombin stimulated release of [3H]arachidonic acid ([3H]AA) accompanied by a significant production of PAF and lyso-PAF by rabbit platelets. These responses, which reflect PLA2 activation, were observed after a prolonged lag and to a lower extent when compared to those induced by alpha-thrombin which evoked a much higher elevation in intracellular calcium. This elevation together with [3H]AA release were markedly reduced by EDTA. However, addition of ionophore A23187 enhanced the release of [3H]AA by gamma-thrombin to the levels similar to those of alpha-thrombin. We conclude that gamma-thrombin is able to activate PLA2 and suggest that calcium influx may be a limiting factor for this activation.
Touqui
L
L
Unité de Pharmacologie Cellulaire, Unité Associée Institut Pasteur/INSERM N. 285, Paris, France.
Jandrot-Perrus
M
M
Vargaftig
B B
BB
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000097:blood; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D004789:Enzyme Activation; D006801:Humans; D007700:Kinetics; D010740:Phospholipases / Q000097:blood*; D010741:Phospholipases A / Q000097:blood*; D054467:Phospholipases A2; D010972:Platelet Activating Factor / Q000032:analysis / Q000096:biosynthesis; D011817:Rabbits; D013329:Structure-Activity Relationship; D013917:Thrombin / Q000502:physiology*
D001095:Arachidonic Acids; D010972:Platelet Activating Factor; D016718:Arachidonic Acid; D000001:Calcimycin; D004492:Edetic Acid; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D013917:Thrombin; D002118:Calcium