cyclic-gmp and trilinolein

Trilinolein, a triacylglycerol with linoleic acid as the only type of fatty acid residue in all three of the glycerol esterified positions, was recently reported to have an antiplatelet effect, mediated through stimulating nitric oxide and cyclic guanosine monophosphate (GMP) formation. In our study, trilinolein induced aggregation of human polymorphonuclear neutrophils (PMNs) and, pretreatment with 0.1 nM trilinolein enhanced phorbol-12-myristate 13-acetate (PMA) induced aggregation. Further investigation showed that trilinolein at concentrations ranging from 0.1 nM to 10 microM increased cyclic GMP formation after 10 min of incubation with PMNs. Pretreatment of trilinolein with 10 microM d-sphingosine, before being incubated with PMNs, attenuated the stimulatory effect of trilinolein on cyclic GMP formation, and pretreatment of 10 microM d-sphingosine also attenuated the aggregation induced by PMA and trilinolein. We conclude that trilinolein can induce the aggregation of human PMNs, and enhance the aggregation induced by PMA.

Topics: Cell Aggregation; Cyclic GMP; Drug Synergism; Enzyme Activation; Free Radicals; Humans; Neutrophils; Protein Kinase C; Second Messenger Systems; Sphingosine; Tetradecanoylphorbol Acetate; Triglycerides

At concentrations ranged from 0.1 nM to 1 microM, trilinolein concentration-dependently relaxed the phenylephrine-induced constriction of isolated rat aorta. Concentration-response curves for the interaction between trilinolein and phenylephrine showed that trilinolein was unlikely a competitive antagonist of phenylephrine. The vasorelaxant effect of trilinolein was dependent on the presence of intact endothelium. Both NG-nitro-L-arginine methyl ester and methylene blue antagonized this vasorelaxant effect. L-arginine partially reversed the effect of L-NAME on trilinolein. Linoleic acid had no vasorelaxant effect. We concluded that trilinolein is an endothelium dependent vasorelaxant and the underlying mechanism could be a stimulation of the nitric oxide and cyclic GMP pathway.

Topics: Amino Acid Oxidoreductases; Analysis of Variance; Animals; Arginine; Cyclic GMP; Dose-Response Relationship, Drug; Endothelium, Vascular; Female; In Vitro Techniques; Male; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase; Rats; Rats, Sprague-Dawley; Triglycerides; Vasodilation

1. Trilinolein, a triacylglycerol with linoleic acid as the only fatty acid residue in all three esterified positions of glycerol, was recently reported to have an inhibitory effect on adrenaline-induced platelet aggregation. In the present study, we found that trilinolein at concentrations ranging from 0.01 to 1 microM increased cyclic GMP formation and decreased cyclic AMP formation in washed human platelets. Both NG-nitro-L-arginine methyl ester (L-NAME) and methylene blue attenuated the trilinolein-induced increase in cyclic GMP. 2. Adrenaline decreased not only the production of cyclic AMP but also that of cyclic GMP. Trilinolein antagonized the inhibitory effect of adrenaline on cyclic GMP formation, but potentiated the inhibitory effect of adrenaline on cyclic AMP accumulation. 3. Both trilinolein and adrenaline enhanced intracellular calcium but the increment of intracellular calcium induced by them was much less than that produced by thrombin. 4. We propose that the anti-platelet effect of trilinolein is mediated through an increase in cyclic GMP, and that the change in cyclic GMP results from stimulation of nitric oxide synthesis in platelets. 5. We also propose that reduction of both cyclic AMP and cyclic GMP are involved in adrenaline-induced platelet aggregation.

Topics: Adult; Blood Platelets; Calcium; Cyclic AMP; Cyclic GMP; Cytosol; Drug Interactions; Epinephrine; Female; Humans; Intracellular Fluid; Male; Nitric Oxide; Platelet Aggregation; Platelet Aggregation Inhibitors; Triglycerides