[The effect of gender on vasomotor function of the vascular endothelium and cardiovascular remodelling during aging].

INTRODUCTION: Aging is correlated with decreased endothelial vasomotor influence, increased carotid intima-media thickness and stiffness, increased left ventricular mass index and increased blood pressure [1-3]. However, these changes are not expressed in the same way in both genders [4, 5]. It seems that females are more protected from cardiovascular changes during aging compared to males [1, 6].

AIM OF THE STUDY: The aim of the study was to evaluate the influence of gender on brachial vasomotor responses (reactive hyperemia test) as well as the correlation with vascular and cardiac remodelling in healthy volunteers of different ages.

MATERIAL AND METHODS: The study was carried out on healthy subjects (n = 66; 37 males, 29 females) of different ages (20-82 years) with no history of cardiovascular diseases and diabetes mellitus. All subjects were normotensive, non-smokers with normal blood lipid and glucose values, were not taking any medication at the time of investigation and were asked to refrain from eating and drinking alcohol, coffee or tea 12 hours before the examination. Subjects were divided in two groups (male and female) and 5 age-related groups according to appropriate decade (20-29, 30-39, 40-49, 50-59, and above 60 years). All subjects underwent regular cardiologic examination, ECG recording and cardiac ultrasound in order to exclude valvular diseases, decreased myocardial contractility and ejection fraction. During the study blood pressure and ECG were recorded continuously. Carotid artery intima-media thickness and brachial artery diastolic internal diameter (mm) and blood flow (ml/min) values were measured continuously using high-resolution ultrasound. Brachial artery parameters were measured in baseline condition, during ischaemia and reactive hyperemia (endothelium-dependent relaxation) and after nitroglycerin administration (endothelium independent relaxation, 2 x 400 micrograms, sublingual) [7, 8]. Brachial ischaemia was induced by inflation of a pneumatic tourniquet placed at the forearm to a pressure of 300 mmHg followed by deflation after 3 min. We analyzed changes in peripheral arteries (changes in brachial artery diastolic diameter and flow during 90 sec after cuff deflation), structural changes of carotid artery, functional and structural changes of the left ventricle (19-11). We used cardiac ultrasound (Hewlett Packard Sonos 2500) with a 2.0-2.5 MHz imaging transducer and a 7.0-MHz linear array transducer for vascular measurements. Demographic and clinical characteristics of subjects are presented in Table 1. All results are expressed as mean and S.E.M. Data analysis was done by linear regression analyses, multivariate test (LSD procedure) and Student's T-test. P values less than 0.05 were considered to be significant.

RESULTS: Relative changes in brachial artery diastolic diameter in reactive hyperemia in comparison to aging (with gender distribution) are shown in Graphs 1 and 2. Our study showed decrease in brachial vasodilator response to reactive hyperemia during aging (male p < 0.05, female p < 0.001). Data analysis showed a significant difference between age-related groups above 40 years and groups below 30 years of age (p < 0.001). The analysis of carotid intima-media thickness showed increased values during aging in both genders but without statistical significance (Graph 2). Analysis of relationship between carotid intima-media thickness and aging (by gender) showed a good correlation of these parameters expressed by the following formula: intima-media thickness (cm) = 0.0009 x years of age + 0.0139. ANOVA test for age-related groups showed significant correlation (p < 0.01) between all age-related groups except 30-40 vs. 40-50 year group. Student's T-test showed no significant correlation between genders. The relationship between the left ventricular mass index (LVMI) and aging (with gender distribution) is shown in Graphs 3 and 4. The left ventricular mass index was increased during aging