Background:Endothelial dysfunction has been implicated in the pathophysiology of cardiovascular diseases, including arterial hypertension. The present study was undertaken to assess endothelial function in postmenopausal women with arterial hypertension receiving hormone replacement therapy and antihypertensive treatment.Material/Methods: A group of 76 women with natural menopause and essential mild to moderate arterial hypertension entered the study. Forty women received a transdermal, combined hormone replacement therapy (HRT) of 17ß-estradiol and norethisterone acetate, whereas 36 served as controls. At baseline and at 3 and 12 months, all patients underwent 24-hr blood pressure monitoring and an exercise test, before which, at peak exercise, and after a 15-min recovery period venous blood was drawn to measure the level of nitrite/nitrate (NOx) according to the Griess method.Results: At 3 and 12 months after beginning HRT, the level of NOx at rest was slightly increased, with marked individual differences in response to HRT. In women not receiving HRT, NOx did not change. In the HRT group, 52.5% at 3 months and 47.5% at 12 months had significantly increased levels compared with the baseline values (17.8±6.7 vs. 32.8±4.5 vs. 28.7±1.1 Kmol/l; p=0.002). The increased NOx level in responders was associated with decreased LDL cholesterol (3.62±1.2 vs. 3.53±1.3 vs. 2.6±0.6 mmol/l; p=0.01). At 12 months, blood pressure values did not differ from those at baseline in either group.Conclusions: The significant increase of NOx in half of the women receiving HRT suggests that only responders experience the cardioprotective effects of HRT.

Keywords: Administration, Cutaneous, Antihypertensive Agents - therapeutic use, Blood Pressure - drug effects, Blood Pressure - physiology, Blood Pressure Monitoring, Ambulatory, Cholesterol, LDL - blood, Endothelium, Vascular - drug effects, Endothelium, Vascular - physiology, Estradiol - administration & dosage, Estradiol - blood, Estradiol - pharmacology, Follicle Stimulating Hormone - blood, Follow-Up Studies, Hormone Replacement Therapy, Hypertension - drug therapy, Hypertension - physiopathology, Nitric Oxide - blood, Nitrites - blood, Norethindrone - administration & dosage, Norethindrone - pharmacology, Postmenopause - drug effects, Postmenopause - physiology, Time Factors, Administration, Cutaneous, Antihypertensive Agents - therapeutic use, Blood Pressure - physiology, Blood Pressure Monitoring, Ambulatory, Cholesterol, LDL - blood, Endothelium, Vascular - physiology, Estradiol - pharmacology, Follicle Stimulating Hormone - blood, Follow-Up Studies, Hormone Replacement Therapy, Hypertension - physiopathology, Nitric Oxide - blood, Nitrites - blood, Norethindrone - pharmacology, Postmenopause - physiology, Time Factors