Title:

The role of autonomic nervous system and selected biochemical parameters in the pathogenesis of hypertension in postmenopausal women

Author:

Pośnik-Urbańska, Aneta

Subject:

biochemical parameters ; menopause ; hypertension ; autonomic nervous system ; women

Abstract:

Summary: Morbidity and mortality from cardiovascular diseases increase rapidly in women after menopause. Past studies indicate a decrease of 17β-oestradiol secretion as an important factor in the pathogenesis of ischaemic heart disease and arterial hypertension. There are some evidences that after menopause the autonomic nervous system dysfunction is the cause of inappropriate regulation of cardiovascular system and its augmented susceptibility for environmental factors. Neuroendocrinic disturbances are strictly connected with metabolic disturbances, and commonly are involved in the development of hypertension. Probably adipocytokines are the important factors binding the sympathetic overactivity with occurrence of hypertension. Some evidences from clinical and experimental studies have inclined to evaluate the participation of these parameters in the pathogenesis of hypertension. Similar role is attributed to brain natriuretic peptide (BNP), although actually only limited studies about its role in patients with mild hypertension exist. There are no evidences about the influence of menopause on BNP level. Present studies indicate to the important prognostic value of these measurements - BNP, adiponectin, leptin and C-reactive protein (CRP) together in evaluation of cardiovascular risk. The aim of this study was evaluation of autonomic nervous system activity in women after men ; opause with mild hypertension and its relationships with above-mentioned hormones and biochemical indicators involved in the development of hypertension in women. We recruited 112 women aged 45 to 55 years (average age 50,73 ± 1,82 years) with mild essential hypertension confirmed by conventional blood pressure measurements and 24 h ABP monitoring (SpaceLabs 90207), without antihypertensive agents during last 4 weeks. The study population were divided into groups - postmenopausal (group A; n = 61; age 51,03 ± 1,39 years) and premenopausal (group B; n = 51; age 50,37 ± 2,19 years). There was no significant difference between groups in age. The postmenopausal period was recognized on base of plasma 17 β oestradiol (< 50 pg/ml), FSH activities (> 30 U/1), and history (a time period from menopause at least 6 months). None of the women had target organ damage - left ventricular hypertrophy, diastolic dysfunction or carotid intima-media thickness 2: 0,9 mm, nor other risk factors - obesity (BMI 2: 30 kg/m2), diabetes mellitus, present or during last 3 months cigarette smoking, inflammation and chronic disorders, taking hormone therapy. Detailed history and physical examination including anthropometric measurements were done in all women. The function of autonomic nervous system was evaluated through heart rate variability in 24 h Holter recordings. Blood levels of creatinine, cholest ; erol and its fractions, leptin, adiponectin, NT-proBNP, C-reactive protein and norepinephrine were measured in each subject. There were no differences between groups in the levels of basic biochemical parameters - creatinine, cholesterol and its fractions. The level of leptin was higher in women after menopause (p <0,05). Positive correlations between leptin and CRP concentrations (r= 0,33; p = 0,0004), and LF (%) at night (r = 0,22; p < 0,02) were observed. Negative correlation between leptin and adiponectin (r = - 0,37; p = 0,00005) was found. Subanalysis revealed that significant correlation between leptin and CRP was present only in premenopausal group (group B; r = 0,43; p = 0,002). The level of adiponectin was lower after menopause (p = 0,007). Negative correlation between adiponectin and CRP (r = - 0,29; p = 0,002), and a positive correlation with LF (%) at night (r = - 0,22; p = 0,02) was observed. The level of NT-proBNP was higher after menopause (p = 0,016). Negative correlations between NT-proBNP and HF(%) 24 h (r = - 0,25; p = 0,009), LF:HF 24h (r = 0,23; p = 0,01), LF (ms) at night (r = 0,21; p = 0,03), HF(%) at night (r = - 0,25; p = 0,008) and LF:HF at night (r = 0,25; p = 0,008) were found. The concentration of CRP was higher after menopause (p = 0,00007). Significant correlations between CRP and average HR 24h (r = 0,31; p = 0,0008), and at night between CRP an ; d LF (%) (r = 0,21; p = 0,03), HF (ms) (r = - 0,22; p = 0,02) and LF: HF (r = 0,21; p = 0,02) were observed. The level of norepinephrine was higher after menopause (p = 0,0009). Negative correlations between the concentration of norepinephrine and total power 24 h (r = - 0,20; p = 0,03) and HF 24h (ms; %) (r = - 0,27; p = 0,004; r = - 0,23; p = 0,02), and between the level of norepinephrine and HF (ms; %) (r = - 0,27; p = 0,005; r = - 0,30; p = 0,002) during a day period were found. Positive correlations between the norepinephrine concentration and LF:HF 24 h (r = 0,25; p = 0,007), during day and at night (r = 0,27; p = 0,004; r = 0,26; p = 0,006) and LF (ms; %) at night (r = 0,28; p = 0,003; r = 0,27; p = 0,005) were present. The average and maximum heart rate were higher in women after menopause (p < 0,00001; p = 0,04). In postmenopausal women lower values of total power (p < 0,000001), VLF (p < 0,001), HF (ms; %) (p < 0,000001) and higher LF (%) (p < 0,000001) and LF: HF 24 h (p < 0,000001) were observed. Summarizing, the balance in autonomic control mechanisms is shifted toward a preponderance of sympathetic efferent activity. Higher level of leptin, NT-proBNP, CRP, norepinephrine, lower concentration of adiponectin, and higher values ofLF, lower HF in women with mild hypertension after menopause indicate that changes in the concentrations of these hormones and markers, and ; dysfunction of autonomic nervous system are the important factors in the pathogenesis of hypertension in this grow up. Postmenopausal women with mild hypertension aged 45 to 55 years are characterized by disturbances in values of time and spectral parameters of heart rate variability, and biochemical parameters. These changes can explain an increase of cardiovascular risk after menopause.

Place of publishing:

Kraków

Level of degree:

2 - studia doktoranckie

Degree discipline:

choroby układu krążenia

Degree grantor:

Wydział Lekarski

Promoter:

Kawecka-Jaszcz, Kalina

Date:

2007

Date issued:

2007

Type:

Praca doktorska

Call number:

ZB-105915

Language:

pol

Access rights:

nieograniczony

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