Estrogen improves endothelial function.
OBJECTIVE
To determine the effect of estrogen on endothelium-dependent relaxation in the cutaneous microcirculation of women.


METHODS
Three groups of women participated in the study. Group 1 (n = 20) was premenopausal and had a mean age of 39 years (range 24-50 years). Group 2 (n = 9) was postmenopausal and had a mean age of 58 years (range 53-65 years). Group 3 (n = 11) was postmenopausal and taking estrogen replacement therapy; the mean age was 53 years (range 43-58 years). Eleven women in group 1 underwent testing twice, once during menstruation (mean serum estradiol level 73 +/- 30 pg/ml) and once during midcycle (mean serum estradiol level 268 +/- 193 pg/ml; p = 0.003). Single-point laser Doppler ultrasound and laser Doppler imaging with a scanner were used to measure vasodilatation in the forearm skin in response to iontophoresis of 1% acetylcholine (endothelium dependent) and 1% sodium nitroprusside (endothelium-independent smooth muscle relaxant).


RESULTS
All three groups were matched for body mass index and fasting glucose, total, high-density lipoprotein, and low-density lipoprotein cholesterol and triglyceride levels. All women had normal blood pressure, and none smoked. Mean serum estradiol levels were 196 +/- 170 pg/ml (group 1), 35 +/- 12 pg/ml (group 2), and 107 +/- 78 pg/ml (group 3) (p = 0.004). Maximum microvascular vasodilatation (percentage increase over baseline) in response to acetylcholine was reduced in group 2 (93% +/- 43%) compared with group 1 (187% +/- 63%) and group 3 (142% +/- 56%) (p = 0.001). The response to sodium nitroprusside also was diminished in group 2 (73% +/- 27%) compared with group 1 (126% +/- 45%) and group 3 (100% +/- 32%) (p = 0.02). Within group 1 the acetylcholine response was higher during the midcycle phase (186% +/- 31%) compared with the menstrual phase (147% +/- 57%) (p < 0.05). The sodium nitroprusside response also was higher during the midcycle phase (144% +/- 31%) compared with the menstrual phase (94% +/- 41%) (p < 0.05)


CONCLUSIONS
The results indicate that estrogens might enhance endothelium-dependent and endothelium-independent vasodilatation in the microcirculation of women.
Arora
S
S
Microcirculation Laboratory, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
Veves
A
A
Caballaro
A E
AE
Smakowski
P
P
LoGerfo
F W
FW
D000109:Acetylcholine / Q000008:administration & dosage; D000293:Adolescent; D000328:Adult; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology; D045166:Estradiol Congeners / Q000494:pharmacology*; D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000502:physiology*; D005260:Female; D005542:Forearm; D006801:Humans; D007478:Iontophoresis; D017078:Laser-Doppler Flowmetry / Q000379:methods; D008597:Menstrual Cycle; D008833:Microcirculation / Q000187:drug effects; D008875:Middle Aged; D009599:Nitroprusside / Q000008:administration & dosage; D012867:Skin / Q000098:blood supply; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
D045166:Estradiol Congeners; D004967:Estrogens; D014665:Vasodilator Agents; D009599:Nitroprusside; D000109:Acetylcholine