Cyclic nucleotides and production of prostanoids in human varicose veins

Objective: Experiments were designed to determine the production of prostac yclin and thromboxane and the activation of cyclic nucleotides in human var icose and nonvaricose veins and to determine whether these second messenger pathways were differentially activated by the venotropic extract of Ruscus aculeatus. Methods: The experiments were designed to characterize the activity of cycl ic nucleotides and the production of prostaglandins in human varicose and n onvaricose veins. Segments of the greater saphenous veins and the adjacent tributaries were obtained from patients who underwent vein stripping and ex cision of primary varicose veins. The saphenous veins from the patients who underwent peripheral arterial bypass grafting were used as controls. The s egments of veins were incubated in Krebs-Ringer bicarbonate solution in the presence of venotropic extract of Ruscus aculeatus (10(-3) g/mL) or in wat er-miscible organic solvent (dimethyl sulfoxide, 10(-3) g/mL), for 1, 5, an d 10 minutes at 37 degrees C. The nonspecific phosphodiesterase inhibitor ( 3-isobutyl-1-methylxanthine, 10(-4) g/mL) was used to block cyclic nucleoti de degradation in some samples. Tissue and media samples were collected. Ti ssue concentrations of both cyclic adenosine monophosphate and cyclic guano sine monophosphate (cAMP and cGMP, respectively) and media concentrations o f 6-ketoprostaglandin-F-1 alpha (the stable metabolite of prostacyclin) and thromboxane B-2 (the stable metabolite of thromboxane A(2)) were measured by means of radioimmunoassay. Cyclooxygenase 2 was measured with Western bl ot analysis. Results: The varicose veins showed greater levels of cAMP but not of cGMP a t all time points as compared with the control veins. Prostanoid production was not significantly altered in the varicose veins. Stimulation with Rusc us aculeatus increased the cAMP concentration in the varicose veins but did not affect the cGMP levels. The ratio between 6-ketoprostaglandin-P-1 alph a and thromboxane B-2 was two-fold greater in the varicose veins as compare d with the control veins. In the presence of the extract, the ratio of 6-ke toprostaglandin-F-1 alpha and thromboxane B-2 was identical in both types o f veins. Cyclooxygenase 2 was not present in either the control or the vari cose veins. Conclusion: These results suggest that cAMP levels are elevated in varicose veins and that they can be altered with drug treatment in varicose veins. This chemical pathway may be considered as a modulatory target to affect co ntraction with venotropic drugs.