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Summary
The aim of this study was to evaluate the association of A1166C polymorphism in angiotensin II type 1 receptor (AT^sub 1^R) gene with baroreflex sensitivity (BRS in ms/mm Hg; BRSf in mHz/mm Hg) in man. BRS and BRSf were determined by a spectral method in 135 subjects (19-26 years) at a frequency of 0.1 Hz. Genotypes were detected by means of polymerase chain reaction and restriction analysis using enzyme DdeI. We compared BRS and BRSf among genotypes of this polymorphism. The frequency of genotypes of AT^sub 1^R A1166C polymorphism was: 45.9 % (AA, n=62), 45.9 % (AC, n=62), 8.2 % (CC, n=11). Differences in BRS (p<0.05) and BRSf (p<0.01) among genotypes of this single nucleotide polymorphism were found (Kruskal-Wallis: BRS - AA: 7.9±3.3, AC: 8.6±3.6, CC: 5.9±2.3 ms/mm Hg; BRSf - AA: 12.0±4.0, AC: 12.0±5.0, CC: 8.0±3.0 mHz/mm Hg). Compared to carriers of other genotypes (AA+AC) the homozygotes with the less frequent allele (CC) showed significantly lower BRSf (Mann-Whitney: BRSf - AA+AC: 12.0±4.0, CC: 8.0±3.0 mHz/mm Hg; p<0.01) and borderline lower BRS (BRS - AA+AC: 8.2±3.5, CC: 5.9±2.5 ms/mm Hg; p=0.07). We found a significant association of A1166C polymorphism in AT^sub 1^ receptor gene with baroreflex sensitivity. Homozygosity for the less frequent allele was associated with decreased baroreflex sensitivity.
Key words
Baroreflex sensitivity * Angiotensin II type 1 receptor * Polymorphism * Spectral analysis
Introduction
Arterial baroreflex is a powerful mechanism of fundamental importance for blood pressure homeostasis. It takes part in both long-term and short-term blood pressure regulation. Though a complex response of the controlling mechanisms mediated by baroreceptors includes the influence on the heart and regulation of the tone of resistance and capacitance vessels, the sensitivity of the baroreceptor-heart rate reflex is studied most frequently (Persson et al. 2001). Under baroreflex sensitivity, usually the change of inter-beat interval in ms or heart rate in mHz due to systolic blood pressure (SBP) change by 1 mm Hg is understood (BRS in ms/mm Hg; BRSf in mHz/mm Hg).
Diminished BRS has been shown to contribute to the pathophysiology of several cardiovascular dysfunctions such as hypertension (Sleight 1997) or cardiac failure (Osterziel et al. 1995). It is associated not only with fully developed hypertension, but it can be seen even in the early...