INTRAPLATELET CYCLIC 3'-5' GUANOSINE-MONOPHOSPHATE IS RELATED TO SERUM-CHOLESTEROL

Nitric oxide (NO) exerts its vasodilator and antiaggregatory effects t hrough activation of soluble guanylate cyclase and the consequent incr ease in the concentration of cGMP in target cells. We conducted this s tudy in order to evaluate relationships between intraplatelet cGMP lev els and risk factors for atherosclerosis in middle aged subjects. Intr aplatelet cGMP was determined by radioimmunoassay and related to age, BMI, blood pressure, antihypertensive treatment, total, LDL and HDL ch olesterol, triglycerides, blood glucose, HbA1c, smoking habit and inti mal thickness of the common carotid artery in 265 subjects participati ng in a health survey (age 59 +/- 6 years, range 48-68 years, 121 fema les, 144 males). Intraplatelet cGMP concentration was inversely correl ated with total serum cholesterol (r = -0.18; p < 0.01) and HDL choles terol (r = -0.14, p < 0.05) as well as with platelet count (r = -0.29; p < 0.001). When platelet count was adjusted for, only the correlatio n between total serum cholesterol and cGMP remained significant. No si gnificant correlations could be demonstrated between intraplatelet cGM P levels and measurable parameters of atherosclerosis. Lower levels of the vasodilating and antiaggregating mediator cGMP in platelets are r elated to higher levels of serum total cholesterol. These results favo ur the hypothesis of a relationship between lipid levels and NO associ ated vasodilator and antiaggregating fuction in atherosclerosis.