Transdermal oestradiol replacement therapy enhances platelet constitutive nitric oxide synthase activity in postmenopausal women with type 2 diabetes mellitus.

OBJECTIVE: To determine whether treatment with transdermal oestrogen replacement therapy (TERT) in postmenopausal women with type 2 diabetes mellitus was able to increase the activity of constitutive nitric oxide synthase (cNOS) in platelets. RESEARCH DESIGN AND METHODS: Eighteen postmenopausal women with type 2 diabetes mellitus (group A) were studied in basal conditions (A1) and on the 10th day of the third month of a sequential opposed TERT (A2) evaluating platelet cNOS activity measured by the conversion of radiolabelled l-arginine to l-citrulline. As a control group (B) 25 normal postmenopausal women underwent the same treatment (B1 and B2 before and during treatment, respectively). RESULTS: Basal values of platelet cNOS activity were superimposable (0.6 +/- 0.1 vs. 0.7 +/- 0.1 fmol/min/109 plts, NS). During TERT, platelet cNOS activity rose in A and B (0.6 +/- 0.1 vs. 1.8 +/- 0.1 fmol/min/109 plts, P < 0.05 and 0.7 +/- 0.1 vs. 2.4 +/- 0.2, P < 0.001, A1 vs. A2 and B1 vs. B2, respectively). However, platelet cNOS activity of A2 did not reach the values of B2 (1.8 +/- 0.1 vs. 2.4 +/- 0.2 fmol/min/109 plts, P < 0.05; A2 vs. B2, respectively). CONCLUSIONS: Sequential opposed transdermal oestrogen replacement therapy was able to increase platelet cNOS activity in postmenopausal women with type 2 diabetes mellitus, suggesting that its use might be positive in preventing cardiovascular pathologies.