Effects of testosterone and estradiol on cutaneous vasodilation during local warming in older men.

Microvascular vasodilation in humans can become impaired with age, leading to cardiovascular diseases ranging from mild to life-threatening. Reproductive hormones may confer some protection on the vascular system in women; however, it is unclear whether the same is true in men. Our goal was to evaluate the impact of four hormonal conditions (testosterone only, estradiol only, testosterone and estradiol, no testosterone and no estradiol) on microvascular vasodilator responsiveness in the skin of older men. We hypothesized that in older healthy men estradiol promotes cutaneous microvascular dilation during local warming of the skin and that testosterone inhibits this dilation. We measured skin blood flow using laser Doppler flowmetry during 35 min of cutaneous local warming to 42 degrees C in 52 healthy men (average age 67 +/- 1 yr). Subjects were randomized to one of the four hormonal conditions and were studied before and after hormone treatments. The endothelium-dependent vasodilator response to local warming was not different among groups either before or after hormone treatment. For example, with testosterone-only treatment this vasodilator response was 220 +/- 13 AU, and with estrogen only the response averaged 246 +/- 12 AU (P > 0.05). We conclude that, within the doses employed in the present study, testosterone and estradiol did not consistently alter cutaneous vasodilator responsiveness in healthy older men.