Summary. Glycoprotein (GP)IIb/IIIa inhibition may abolish activated leukocyte-induced platelet activation, in which leukocyte-released platelet-activating factor (PAF) is a major mediator. The present study thus investigated if and how GPIIb/IIIa inhibitors interfere with PAF-induced platelet activation. Platelet and leukocyte activation were monitored by¯ow cytometry and immunoblotting. GPIIb/IIIa inhibitors (c7E3, non-peptide SR121566, and MAb RFGP56) attenuated PAF-induced, but not adenosine diphosphate (ADP)-or thrombin receptor activating peptide (TRAP)-induced platelet P-selectin expression in whole blood. GPIIb/IIIa blockade enhanced ADP-or TRAPinduced leukocyte CD11b expression, but not the response to PAF. GPIIb/IIIa blockade attenuated PAF-induced, but enhanced ADP-or TRAP-induced platelet±leukocyte aggregation. Under the present experimental conditions, thromboxane A 2 receptor antagonism did not signi®cantly in¯uence PAFinduced platelet activation, and GPIIb/IIIa inhibition did not interfere with calcium mobilization/in¯ux in platelets. Protein kinase C (PKC) blockade inhibited PAF-induced platelet P-selectin expression, and PAF-induced PKC activity was reduced by GPIIb/IIIa inhibition. PAF (1 mM) did not induce MEK 1/2 or ERK 1/2 phosphorylation, whilst thrombin induced marked responses, which were enhanced by GPIIb/IIIa blockade. Thus, GPIIb/IIIa inhibition attenuates PAF-induced platelet activation via inhibiting PKC activity. GPIIb/IIIa blockade enhances thrombin-induced platelet MEK 1/2 and ERK 1/2 activation, and augments ADP-and TRAP-induced leukocyte activation by enhancing platelet±leukocyte aggregation.

We conclude that 2500 ml of electrolyte-free irrigating fluid had no detrimental effects on kidney function in sheep. The changes we observed were essentially the same as after infusion of isotonic saline.