SEX AND AGE-DIFFERENCES IN SOLUBLE GUANYLATE-CYCLASE ACTIVITY IN HUMAN PLATELETS

Soluble guanylate cyclase is a key enzyme of nitric oxide (NO)-related intracellular signal transduction in platelets. In the present study, we investigated the effects of sex and age on the enzyme activity in human platelets. Soluble guanylate cyclase activity was determined by generation of cyclic GMP in platelet cytosol. No significant differenc es in the basal activity of soluble guanylate cyclase were observed be tween in men and women, and between in young and old subjects. However , soluble guanylate cyclase activity in response to sodium nitroprussi de, an exogenous NO donor, was higher in young men than in young and o ld women. Furthermore, the enzyme activity was lower in old than in yo ung men, but there were no differences in female platelets between fro m young and old subjects. The present data suggest that NO-related sig nal transduction system in the platelet is affected by sex and age, wh ich, to certain extent, contributes to different sensitivity of human platelets.