Nitric oxide and platelet energy metabolism

This study was undertaken to determine whether nitric oxide (NO) can affect platelet responses through the inhibition of energy production. It was found that NO donors: S-nitroso-N-acetylpenicyllamine, SNAP, (5–50 M) and sodium nitro-prusside, SNP, (5–100 M) inhibited collagen- and ADP-induced aggregation of por-cine platelets. The corresponding IC50 values for SNAP and SNP varied from 5 to 30 M and from 9 to 75 M, respectively. Collagen- and thrombin-induced platelet secre-tion was inhibited by SNAP (IC50 = 50 M) and by SNP (IC50 = 100 M). SNAP (20–100 M), SNP (10–200 M) and collagen (20 g/ml) stimulated glycolysis in in-tact platelets. The degree of glycolysis stimulation exerted by NO donors was similar to that produced by respiratory chain inhibitors (cyanide and antimycin A) or uncouplers (2,4-dinitrophenol). Neither the NO donors nor the respiratory chain blockers affected glycolysis in platelet homogenate. SNAP (20–100 M) and SNP (50–200 M) inhibited oxygen consumption by platelets. The effect of SNP and SNAP on glycolysis and respiration was not reduced by 1H-[1,2,4]oxadiazo-lo-[4,3-a]quinoxalin-1-one, a selective inhibitor of NO-stimulated guanylate cyclase