PEPTIDE-204-212 OF LIPOCORTIN-5 INHIBITS THE GENERATION OF A PROSTACYCLIN-LIKE FACTOR FROM RAT AORTA PREPARATIONS INVITRO

The release of an endogenous prostacyclin-like factor (PLF) from rat thoracic aorta rings was evaluated through inhibition of platelet ADP-induced aggregation and assessed with a micro-method using 96-multiwell plates. Aggregation was assessed in an ELISA reader by measuring changes.of optical density at 620 nm in each well. The generation of endogenous PLF by aortic rings was time-dependent and was inhibited by indomethacin (3 muM). ADP-induced aggregation was inhibited by iloprost in a dose-dependent manner. Incubation of rat aorta rings with peptide 204-212 of human lipocortin 5 (1-100 mug/ml) resulted in a dose-dependent inhibition of PLF release with a maximal inhibition of 90-95%. The effect of peptide 204-212 was reversible. A control peptide (amino-acids 104-112 of lipocortin 5) was without any significant effect. Peptide 204-212 (100 mug/ml) did not modify PLF release from rat aorta preparations challenged with arachidonic acid (10(-6)-10(-4) M).