Endothelium plays an important role in controlling the vascular tone, ensuring the regulation of the lumen of the vessel, depending on the speed of blood flow and blood pressure. One of the main biologically active substances that is synthesized by the endothelium is nitrogen oxide (NO), which has a vasodilatating effect. There are a number of factors that have a negative influence on endothelial function. Among them an important role is played by the hyperactivation of the renin-angiotensin-aldosterone system (RAAS), which leads to arterial hypertension, and subsequently to ischemic heart disease.
The aim of our study was to find out the relationship between hemodynamic parameters and the functional condition of endothelial function in healthy men.
The subject of this study were 36 young men with age from 18 to 25. The weight, BMI and the indices of body composition: percentage of body fat (BF, %), percentage of fat-free mass (FFM, %), visceral fat (VF) were measured by body-analizator Tanita BC-601(Japan). The function of cardiovascular system was measured by using medical device ‘REOKOM’ (Ukraine). We measured cardiac output (CO), stroke volume (SV), system vascular resistance (SVR). We used non-invasive method to test the functional condition of endothelium, by causing endothelium-dependent vasodilatation (device ‘REOKOM’, Ukraine).
Multiple regression analysis was conducted to examine the relationship between hemodynamic parameters and functional condition of the endothelial function. The one of the multiply regression models consist of such predictors as SV, CO and indices of SV and CO. This model was statistically significant- Fisher’s criterion F = 2,744, p < 0.046, determination coefficient was – R2 = 0.26, which suggests a relatively low predictive value of the model. The greatest impact on endothelial function has SV (b * -10.39). If SV increase on 1 ml, the endothelial function will decrease on 3.48 % (p < 0.011). The second largest influence on endothelial function has CO (b* = 9.22). If CO increases on 1 l / min, the endothelial function will increase on 48.7 % (p < 0.014). Another multiply regression model includes such predictors as workload of left ventricle (LV), index of workload of LV and parameter of power contraction of LV. This model did not show significant result- Fisher’s criterion F = 1.67, p > 0.191, determination coefficient was – R2 = 0.135.
These findings suggest that endothelial function has statistically significant connection with SV and CO in young healthy men. Long-term vasodilatation of vessels due to the high levels of SV and CO leads to remodeling of the endothelium with a decrease in the synthesis of vasodilatory substances and damage of endothelial cells. This, in turn, leads to initial manifestations of endothelial dysfunction, characterized by an increase in the synthesis of vasoconstrictors, and actually an increase in blood pressure and rigidity of the walls of the vessels. The influence of other hemodynamic parameters on the function of the endothelium needs further study.
Keywords: endothelial function; cardiac output; nitrogen oxide; vasodilatation; shear stress
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