PLATELET CNOS ACTIVITY IS REDUCED IN PATIENTS WITH IDDM AND NIDDM

Several studies in vitro and in vivo suggest that the nitric oxide (NO ) production is impaired in diabetes mellitus. Reduced levels of NO co uld contribute to vascular alteration facilitating platelet-vascular w all interaction, adhesion of monocytes to endothelium, vascular smooth muscle proliferation and by decreasing endothelium-dependent vasodila tion. In this study we evaluated the activity of the constitutive nitr ic oxide synthase (cNOS) in platelets of patients with insulin-depende nt diabetes mellitus (IDDM) and with non-insulin-dependent diabetes me llitus (NIDDM). When compared to that of normal subjects, cNOS activit y is significantly lower in patients with IDDM and with NIDDM (1.57 +/ - 0.25 vs. 0.66 +/- 0.10 fmol/min/10(9) PLTs and 1.57 +/- 0.35 vs. 0.6 7 +/- 0.08, respectively; p <0.005). These data demonstrate that the p latelet cNOS activity is decreased in diabetes mellitus.