C-natriuretic peptide – as an indicator of persistent increase in blood pressure in men with hypertension

Abstract

Annotation. According to multiple studies hypertension (AH) is a multifactorial disease. It is recognized that one of the key mechanisms of persistent increase in blood pressure (BP) is the imbalance between vasoconstriction and vasodilation and endothelial dysfunction (ED) is one of the leading links in the pathogenesis of AH. The consequence of ED is a persistent vasoconstrictor reaction which results in myocardial remodeling in the form of left ventricular hypertrophy (LVH) and the subsequent development of congestive heart failure (CHF). One of the most important representatives of the group of vasoconstrictor peptides is endothelin-1 (ET-1). It has been previously shown that the polymorphism of the gene encoding it (Lys198Asn) is associated with fluctuations in ET-1 plasma concentration. In this regard, the corresponding changes in plasma levels of one of the most powerful vasodilators – C-natriuretic peptide (CNP) – remain poorly understood. CNP is a direct antagonist of ET-1 which increases in the blood in AH and can be used as a screening method to identify patients with high BP. The aim of the study – improving the detection of men with AH who has persistent long-term elevations in BP by using the plasma level of CNP and taking into account the carrier of polymorphic variants of the ET-1 gene. The study involved 191 men aged 40-60 years: 79 men were from control group, 62 patients with AH and LVH and 50 patients with AH complicated by CHF II-III classes for NYHA. Enzyme-linked immunosorbent assay was used to determine the plasma concentration of CNP. Genotyping of the ET-1 gene was performed using the polymerase chain reaction. Mathematical processing was performed on a personal computer using the standard statistical package STATISTICA 6.0. It is established that plasma CNP levels in men with AH and LVH (5.21±0.11) pmol/ml and in patients with AH and CHF (5.22±0.13) pmol/ml are significantly higher than in control patients (2.35±0.06) pmol/ml (p<0.0001) however did not differ in patients with AH from different groups. The obtained results allowed to calculate the limit level of CNP which is ≥3.37 pmol/ml and can be used for screening detection of males with persistently elevated BP in the survey of large populations. It was found that in patients with AH as in the control group the Lys/Lys genotype and the Lys allele of the ET-1 gene predominate. There was no significant difference in the frequency of ET-1 gene between groups (p>0.05). It should be noted that in patients with AH carrying all polymorphic variants of the ET-1 gene the level of CNP in blood was also significantly higher than in the control group, however in carriers of the Asn allele plasma level of CNP is higher than in individuals with the Lys/Lys genotype in all study groups. So it was investigated that the average plasma concentration of CNP in patients with AH is higher than in the control group which made it possible to establish a limit level of peptide for screening of individuals with persistent long-term elevation of BP. In men of the control group and in patients with AH the carrier of the Asn allele of the ET-1 gene is associated with a higher level of CNP but in all study groups the Lys/Lys genotype and the Lys allele of the ET-1 gene were dominant.