Joanna Ziemak

The associations between G972R polymorphism of the IRS-1 gene, insulin resistance, salt sensitivity and non-dipper hypertension

The aim of this study was to assess the association between G972R polymorphism of the insulin receptor substrate-1 (IRS-1) gene and the circadian variation in blood pressure, insulin sensitivity and salt sensitivity in subjects with uncomplicated, never-treated essential hypertension receiving low-, normal- and high-salt diets. The study was performed on 115 subjects aged 27.48±5.1 years with never-treated, uncomplicated hypertension. In the 7-day consecutive period of time, subjects received a normal-, low- and high-salt diet. At the end of each dietary regimen, the following parameters were recorded: 24-h blood pressure monitoring, lipid profile, insulin level, glucose level, aldosterone level and plasma renin activity. Insulin resistance was evaluated by the homeostasis model assessment (HOMA). In comparison with Gly/Gly carriers, subjects with the G972R polymorphism had higher concentrations of total and LDL cholesterol and triglycerides and HOMA but lower HDL cholesterol. On a high-salt diet, patients with the G972R polymorphism had an increased risk for insulin resistance (odds ratio (OR)=11.42, 95% confidence interval (CI) 7.68–28.44), salt sensitivity (OR=5.38, 95% CI 1.14–25.34) and non-dipper hypertension (OR=3.6, 95% CI 1.07–12.09). Regardless of the dietary salt intake, blood pressure values were similar between G972R and Gly/Gly carriers. In conclusion, the results of our study suggest that the G972R polymorphism of the IRS-1 gene is associated with insulin resistance, salt sensitivity and non-dipper hypertension.

Associations of the –344T>C polymorphism of CYP11B2 gene with 24-hour blood pressure profiles in middle-aged women with essential hypertension

Background In this cross-sectional study, we assessed the impact of –344T>C polymorphism of the CYP11B2 gene which encodes aldosterone synthase on 24-hour blood pressure patterns. Material and methods The study was performed in 137 females with essential hypertension aged 42−60 years. We measured plasma aldosterone level and renin activity (PRA), fasting glucose, lipid profiles and 24-hour urinary sodium and potassium excretion. Based on 24-hour blood pressure monitoring we identified cases with dipping and non-dipping patterns of blood pressure. Results Mean PRA and aldosterone levels and aldosterone-to-renin ratio (ARR) were within normal range. Non-dipping hypertension was found in 54.3% of patients. Genotype frequencies of TT, CC and CT were 27%, 27% and 46%, respectively. Carriers of the C allele had significantly lower nocturnal blood pressure reduction (P = 0.004) and higher nocturnal systolic (P = 0.02) and diastolic blood pressure (P = 0.044), frequency of non-dipping profile (P = 0.001), and 24-hour urinary potassium excretion (P = 0.047). Urinary sodium excretion was positively correlated with a decrease in nocturnal blood pressure (R = 0.202; P = 0.037). In a multiple regression analysis, ARR and presence of the C allele adjusted for confounding variables were inversely associated with the nocturnal blood pressure decline (b = −0.348; P = 0.022 and b = −0.222; P = 0.018, respectively). Conclusions In conclusion, in middle-aged females with essential hypertension carrying the C allele we found higher nocturnal blood pressure, lower nocturnal blood pressure reduction, and higher prevalence of non-dipping hypertension than in TT carriers.

The influence of varying dietary sodium content on circadian blood pressure profile in patients with salt-sensitive hypertension

The pathogenesis of essential hypertension is not fully understood. Literature indicates the complexity of blood pressure regulating mechanisms with a high impact of genetics and environmental factors. Previous experimental studies have shown the importance of salt intake in the development of hypertension. The aim of the study was to explore the influence of varying dietary sodium content on circadian blood pressure profile in patients with salt-sensitive hypertension. The study was carried out among 69 salt-sensitive hypertensive patients (19 females i 50 males) mean aged 36.1 ± 8.0 years. Study protocol provided low sodium diet firstly then high sodium diet containing 10–20 mmol and 220–240 mmol of sodium per day respectively. On each of the diet ABPM was performed. Our results suggest that in salt-sensitive patients the reduction of salt intake may decrease blood pressure and restore its circadian profile and thus lead to the reduction in the rate of complications of hypertension.

Testosterone assocition with blood pressure profile and left ventricular mass in a young hypertensive population

Sex hormones not only regulate the gonads function, but also may affect the cardiovascular system, although their role is still not clear. Testosterone influence on arterial pressure and left ventricular hypertrophy were widely reported. A number of factors have been implicated as the underlying cause of the relation between testosterone and blood pressure, including sex and age as most important ones. In present findings, a 24-hour ABPM revealed that 33.9% of patients had an altered pattern of blood pressure with no significant differences between sexes. In the whole studied sample, positive correlation has been found between testosterone and 24-hour systolic blood pressure, daytime BP, sodium and potassium levels in the 24-hour urine collection, and left ventricular mass index. In conclusion, testosterone association with blood pressure profile and left ventricular mass in a young hypertensive population seems to be probable, but further analysis is necessary.

Comparison of the concentration of leptin between obese women and obese men with essential hypertension

Background The main determinants of the level of leptin in human plasma are the fat mass and sex. In recent literature many papers have been published indicating the participation of leptin in the pathogenesis of essential hypertension. The aim of this study was to compare serum levels of leptin and evaluate its importance in the pathophysiology of hypertension in obese men and women. Material and methods The study was conducted in a group of a total of 52 obese individuals (26 women and 26 men) with newly diagnosed essential hypertension. The study protocol included blood sample collection for the measurements of biochemical parameters and hormone levels. Biochemical assays were performed using routine methods. Serum insulin was determined by immunoradiometric assay (IRMA). The index of insulin resistance (IR) was calculated using HOMA. Leptin, plasma renin activity (PRA) and plasma aldosterone concentration were determined by radioimmunoassay (RIA). Results No significant differences were found between women and men in terms of age, BMI, blood pressure, total cholesterol, LDL and fasting glucose. Men had slightly but significantly higher waist circumference. The group of women had significantly higher levels of leptin, insulin and insulin resistance, and a higher PRA and aldosterone levels than males. In the group studied, leptin significantly positively correlated with blood pressure, as well as with the concentration of aldosterone and renin both in women and in men. There was no similar relationship between leptin and insulin and the insulin resistance index. Conclusions Women with obesity and hypertension have higher levels of leptin than obese men with hypertension. Reported correlations between plasma leptin concentration and blood pressure suggest that it is directly or indirectly involved in the pathophysiology of hypertension in obese individuals regardless of gender.