RESEARCH ARTICLE PKC and AKT Modulate cGMP/PKG Signaling Pathway on Platelet Aggregation in Experimental Sepsis

Sepsis severity has been positively correlated with platelet dysfunction, which may be due to elevations in nitric oxide (NO) and cGMP levels. Protein kinase C, Src kinases, PI3K and AKT modulate platelet activity in physiological conditions, but no studies evaluated the role of these enzymes in platelet aggregation in sepsis. In the present study we tested the hypothesis that in sepsis these enzymes positively modulate upstream the NO-cGMP path-way resulting in platelet inhibition. Rats were injected with lipopolysaccharide (LPS, 1 mg/ kg, i.p.) and blood was collected after 6 h. Platelet aggregation was induced by ADP (10 μM). Western blotting assays were carried out to analyze c-Src and AKT activation in plate-lets. Intraplatelet cGMP levels were determined by enzyme immunoassay kit. Phosphoryla-tion of c-SRC at Tyr416 was the same magnitude in platelets of control and LPS group. Incubation of the non-selective Src inhibitor PP2 (10 μM) had no effect on platelet aggrega-tion of LPS-treated rats. LPS increased intraplatelet cGMP levels by 5-fold compared with control group, which was accompanied by 76 % of reduction in ADP-induced platelet aggre-gation. The guanylyl cyclase inhibitor ODQ (25 μM) and the PKG inhibitor Rp-8-Br-PET