Background: Studies have shown that chronic oestrogen treatment improves both lipid profile and vascular reactivity in postmenopausal women, in whom it also appears to have a beneficial effect on vascular haemodynamics and compliance. Whether oestrogen has a similar effect in men is unknown.
Objective: To determine whether long-term oestrogen treatment alters arterial compliance and haemodynamics in biological males.
Methods: We compared the effects of chronic oestrogen treatment on blood pressure, heart rate and arterial compliance in 21 male-to-female transsexuals prescribed long-term oestrogen treatment with those in 20 age-matched healthy males. Systemic arterial compliance was assessed using the 'area method', by the simultaneous measurement of aortic flow and driving pressure.
Results: Mean systemic arterial compliance was similar in transsexuals and age-matched males (mean +/- SE 0.66 +/- 0.06 ml/mmHg compared with 0.58 +/- 0.05 ml/mmHg, P = 0.34). These results did not differ after the exclusion of transsexuals with coronary risk factors or vascular disease. Heart rate (67 +/- 2 beats/min compared with 64 +/- 3 beats/min, P = 0.41), systolic blood pressure (119 +/- 3 mmHg compared with 119 +/- 2 mmHg, P = 0.95), pulse pressure (55 +/- 3 mmHg compared with 50 +/- 2 mmHg, P = 0.13), diastolic blood pressure (64 +/- 2 mmHg compared with 69 +/- 2 mmHg, P = 0.06) and mean arterial pressure (84 +/- 2 mmHg compared with 89 +/- 2 mmHg, P = 0.09) were also similar at baseline between the two groups. Serum testosterone (an index of oestrogen treatment) was markedly suppressed in the transsexuals compared with the males (0.8 +/- 0.5 nmol/l compared with 25.3 +/- 12.6 nmol/l, P < 0.0001). Univariate analysis revealed that the best predictors of arterial compliance were the pulse pressure (rs = -0.41, P = 0.02) and the systolic blood pressure (rs = -0.35, P = 0.02). On multivariate analysis, the best combination of predictors of compliance were the pulse pressure, testosterone and low-density lipoprotein cholesterol concentrations (R2 = 0.29, P = 0.01).
Conclusions: Although previous evidence suggests chronic oestrogen treatment can improve endothelium-dependent vasodilatation and favourably alter the lipid profile in biological males, these changes are not reflected in changes in systemic arterial compliance. Changes in arterial compliance may not be central to the beneficial effects of oestrogen on vascular function, at least in males.