Corresponding author: Tatyana N. Malorodova (
Academic editor: Lev Sernov
Antiarrhythmic drugs have been in use for over 100 years to prevent and treat heart rhythm disorder despite many limitations and adverse effects (Castro et al. 2015). Their role of being the essential part of antiarrhythmic therapy inspires researchers to create novel molecules all over the world.
The mechanism of action is the cornerstone, which determines the therapeutic effectiveness and safety profile of an antiarrhythmic drug. It might be defined as an assembly of functional transformations of intracellular homeostasis and extracellular interaction that ultimately determines the pharmacological Ultrasonic dopplerography is a valuable diagnostic tool that allows the assessment of the functional state of the vasculature in the norm and in the case of pathology (
In addition, in clinical settings where sampling is not always possible, the use of the Pourcelot index (
The purpose of this study is to optimise the approach for assessing the endothelial dysfunction in the case of ultrasound recording of blood flow velocity by studying the correlation between the dynamics of blood flow velocity changes in the femoral artery, arterial pressure and linear microcirculation rate when undertaking functional tests in the presence of activation and blockade of endogenous nitric oxide synthesis.
The study was conducted on 18 male Wistar rats weighing 180210 g, which were all obtained from The Stolbova nursery of the RussianAcademy of Medical Sciences (Moscow region) at the same time. All activities with the animals were carried out in compliance with
The animals were divided into two equal groups: 1) intact; and 2) with nitroLarginineinduced (LNAMEinduced) endothelial dysfunction (by administering LNAME intraperitoneally 25 mg/kg once a day for seven days) (
After the anaesthetised rats (chloral hydrate 150 mg kg, zoletil 60 mg/kg) had been fixed on the stage, their right carotid artery and their right femoral neurovascular bundle were isolated and their left femoral vein was catheterised.
For a multicomponent study of haemodynamic parameters affected by the administration of acetylcholine and sodium nitroprusside, the systemic arterial pressure, the velocity of blood flow in the femoral artery and the rate of microcirculation in the thigh muscle tissue, which the femoral artery supplies with blood, were recorded. Systolic blood pressure (
Thus, the possibility of concurrent monitoring of the parameters for haemodynamics and microcirculation at three levels in the system “centre – elastic vessel – peripheral blood flow” was obtained. Statistical processing of the results was carried out by means of STATISTICA 10.0 and Microsoft Excel 2013. A statistical analysis for the correlation was made using Spearman’s rank test. The significance of the intergroup differences was statistically tested by the Student’s test.
The intact rats gave the same response to the administration of acetylcholine and sodium nitroprusside, which showed in: 1) a decrease in of
Endotheliumdependent (acetylcholine) and endotheliumindependent (nitroprusside) vascular reactions in intact rats (
For further statistical processing, a number of values over time for each sample were expressed as a percentage, where the initial value was taken as 100% according to the formula: value/initial value×100%. Statistical analysis using the Spearman’s rank test showed that, in both samples, the dynamics of many of the parameters under study correlated reliably between each other (Table
Spearman’s Correlation Coefficients Revealing the Link Between the Dynamics of Changing Values Obtained When Measuring mean BP, Linear Microcirculation Rate and Doppler Sonography (









Mean BP  0.72*  0.69*  0.86*  0.71*  0.71*  1 
Linear microcirculation rate  0.46*  0.39*  0.52*  0.45*  0.49*  0.57* 









Mean BP  0.71*  0.69*  0.82*  0.69*  0.68*  1 
Linear microcirculation rate  0.49*  0.41*  0.51*  0.68*  0.61*  0.69* 









Mean BP  0.71*  0.68*  0.85*  0.76*  0.71*  1 
Linear microcirculation rate  0.49*  0.41*  0.52*  0.42*  0.40*  0.59* 









Mean BP  0.72*  0.71*  0.86*  0.70*  0.73*  1 
Linear microcirculation rate  0.51*  0.41*  0.52*  0.41*  0.41*  0.54* 
Key:
The highest degree of correlation at p<0.05 was found between such indicators as mean BP, linear microcirculation rate, systolic velocity and systolicdiastolic velocity difference in the femoral artery (
Scatter graph, representing the dependence of the mean BP and systolicdiastolic velocity difference when administering acetylcholine to the intact animals.
Scatter graph, representing the dependence of the mean BP and the maximum systolic velocity when administering acetylcholine to the intact animals.
Scatter graph, representing the dependence of the mean BP and maximum diastolic velocity when administering sodium nitroprusside to the intact animals.
As in the group of the intact animals, in the group of the animals with LNAMEinduced endothelial dysfunction, the greatest correlation with the indicators of systemic and local haemodynamics was found for such dopplerographic parameters as
The obtained results indicate that the blood flow parameters
Using regression analysis, the hypothesis that the relationship between the dynamics of the parameters under study obeys a linear equation was tested. Using STATISTICA 10.0 software, the formulae describing the dependence of the parameters under study for the following pairs are defined: 1)
where, x –
Y – mean BP, Linear microcirculation rate;
k_{1} k_{2}, m – empirically calculated coefficients
The values of k_{2} were significantly smaller than those of k_{1} (56 orders of magnitude less), which indicates their insignificant contribution and makes it possible to neglect them and to form an opinion about the predominance of the linear form of the dependence between the parameters under study. This circumstance makes it clear that their changes occur proportionally regardless of the initial values.
Since the endothelial function can be assessed by the difference in responses to the endotheliumdependent and endotheliumindependent test, the next step was a quantitative analysis of the results obtained and an assessment of the intensity of the reactions recorded when measuring the central and peripheral parameters of haemodynamics. Using Microsoft Excel 2013 software, the areas formed by the curves of changes in arterial blood pressure, microcirculation rate,
where X –
Then, for the parameters under study, the average ratio S_{NP}/SAСwas determined, where in the Doppler study, S_{NP} – the area under the rise curve of the values of
Reaction Areas for the Parameters Under Study and Their Ratio When Administering Acetylcholine and Sodium Nitroprusside to the Group of Intact Rats (n = 9) and to the Group of Animals with LNAMEinduced deficiency of nitric oxide (n = 9).
Reaction Areas for the Parameters Under Study and Their Ratio When Administering Acetylcholine and Sodium Nitroprusside to the Group of Intact Rats  






S_{AС}  1801.3±92.25  1987.2±123.13  1254±101.84  2357.9±201.13 
S_{NP}  1910.5±121.14  2165.4±121.80  1369.1±122.70  2601.6±256.53 
S_{NP}/S_{AС}  1.12±0.06  1.10±0.06  1.09±0.05  1.15±0.11 







S_{AС}  842.3±32.23  940.2±43.12  709±93.90  1007.8±199.32 
S_{NP}  2501.5±132.43  2798.4±143.76  1969.1±223.62  3211.5±356.57 
S_{NP}/S_{AС}  3.94±0.27  3.99±0.29  4.05±0.31  4.11±0.52 
Key: henceforward, S_{NP} – the area under the curve of
A statistical analysis of significance of differences in S_{NP}/S_{AС,} calculated by the parameters
Intergroup pairwise comparison of the group of intact animals with the group of animals with LNAMEinduced deficiency of nitric oxide by the following parameters under study:
Earlier in our laboratory, it was shown that, when undertaking functional vascular tests with a prolonged, within 7 days, intraperitoneal administration of LNAME at a dose of 25 mg/kg in laboratory animals, there appeared a complex of functional and morphometric changes associated with the development of a deficiency of nitric oxide due to the blockade of NOsynthase. The dynamics of arterial pressure indices was assessed by calculating the areas of the triangles above the reaction curve for restoring the mean arterial pressure after the administration of nitroprusside and above the reaction curve for restoring the mean arterial pressure after the administration of acetylcholine. To evaluate the endothelial function, the endothelial dysfunction coefficient was proposed, which is determined by calculating the ratio between the area of the triangle above the reaction curve for restoring the mean arterial pressure after the administration of nitroprusside and the area of the triangle above the reaction curve for restoring the mean arterial pressure after the administration of acetylcholine (
In this study, in order to analyse the data obtained, the area of reactions under the curve of
In the multicomponent study of haemodynamic parameters and microcirculation affected by undertaking pharmacological tests, the greatest correlation between the blood flow velocity parameters of the femoral artery (
Despite the fact that the resistivity and pulsatility index consider the difference component of
The combined evaluation of the results obtained suggests that noninvasive ultrasound dopplerography using the ΔVs
1. When calculating the ratio of areas of S_{NP}/S_{AС} under the curve of the dynamics of systolic blood flow velocity changes and systolicdiastolic difference in blood flow velocities in the femoral artery, the linear microcirculation rate, as well as that above the curve of the dynamics of the mean BP change between the group of the intact animals and the group of the animals with LNAMEinduced endothelial dysfunction, a significant difference in the studied parameters was found. The abovementioned confirms the possibility of applying a calculated ratio of reaction areas under the curve of systolicdiastolic difference in blood flow velocities after the administration of sodium nitroprusside and acetylcholine to assess the endothelial function.
2. In conducting functional vascular tests, both in the group of the intact animals and in the animals with LNAMEinduced deficiency of nitric oxide, a high degree of correlation was found between the changes in mean BP, systolic blood flow velocity (