#3406 CARDIOPROTECTIVE EFFECT OF SOY PROTEIN ON LONG-TERM HIGH-SALT DIET IN CYNOMOLGUS MONKEYS
Authors: Kulikov Aleksander , Beresneva Olga , Ivanova Galina , Parastaeva Marina , Kucher Anatoly , Khasun Mokhamad , Orlov Sergey 
Published: June 2023

Abstract

Background and Aims
A high salt content in the diet is one of the reasons for the increase in blood pressure (BP) and the development of cardiovascular disorders. However, high intake of sodium chloride does not always lead to an increase in blood pressure, but causes endothelial dysfunction and cardiac remodeling. It has been established that the introduction of soy products into the diet can have a nephro- and cardioprotective effect in chronic kidney disease. At the same time, it is not clear whether the damaging effect of a high-salt diet on the cardiovascular system can be offset by other dietary interventions, in particular, soy proteins. In this regard, the aim of the study was to study the effect of long-term use of diets with different content of sodium chloride and soy protein on myocardial remodeling in cynomolgus monkeys.

Method
A total of 18 cynomolgus male monkeys with age 6–8 years were studied. The animals were divided into three groups (six in each group). The first (control) group received the standard diet. The second group received the diet rich in common salt (8 g of NaCl/kg), and the third, the high salt diet in combination with soy protein SUPRO 760 (200 g/kg; Protеin Tеchnology Intеrnational, USA). Systolic (BP) and diastolic (BPd) blood pressure (BP) in monkeys was recorded by oscillometric method on a veterinary tonometer ML-410 VET (Microlux, Russia) under anesthesia. After registration of blood pressure, an echocardiographic study (EchoCG) was performed with a sector sensor with a frequency of 3-5 MHz on an ultrasound system Chison SonoTouch 60 (China). Echocardiography was performed in B-mode (two-dimensional scanning), M-mode (one-dimensional scanning), as well as in pulsed and tissue Doppler modes. Echocardiography and blood pressure measurements were performed at baseline, after 4 and 12 months of follow-up.

Results
BP values (group 1 - BPs: 109±10.09, BPd: 60±7.42; group 2 - BPs: 109±25.14, BPd: 57±11.86; group 3 - BPs: 101±8, 59, BPd: 57±6.92 mm Hg, all p&gt;0.05) and heart rate (group 1 - 77±12.61, group 2 - 81±18.07, group 3-80±19.9 beats/min, all p&gt;0.05) in macaques did not undergo significant changes over 12 months of the experiment in any of the groups. In group 1, there were also no significant changes in echocardiographic parameters. Group 2 monkeys showed no early changes in LV shortening fraction (FU) and ejection fraction (EF). However, after 12 months, FU decreased by an average of 26.6%, and EF by 12.8% compared with the indicator for a period of 4 months. In addition, the speed of the transmitral flow in early diastole (E) decreased by 19.1% compared with the baseline. Long-term intake of soy proteins prevented a decrease in LV FU in macaques on a high-salt diet. Its value was 25.1% greater than in group 2. In group 3 monkeys, after 12 months, the magnitude of systolic excursion of the mitral annulus plane and the maximum rate of excursion of the fibrous annulus of the mitral valve in early diastole (e') increased, the thickness of the interventricular septum in diastole decreased, and E/e' ratio. In group 3, the thickness of the posterior wall of the left ventricle decreased in systole (0.57±0.056 mm), the mass of the LV myocardium (14.9±2.94 g/m2), the average diameter of the base of the right ventricle (1.20±0.115 mm) compared with group 2 (0.69±0.040 mm, 19.6±2.83 g/m2, 1.40±0.111 mm, respectively; all p&lt;0.01).

Conclusion
The obtained results can be considered as confirmation of the hypothesis that high consumption of sodium chloride leads to adverse structural and functional changes in the heart and blood vessels, not associated with an increase in blood pressure. The inclusion of isolated soy proteins in the diet is likely to reduce the effects of this negative impact. The specific mechanisms of this cardioprotective effect remain to be explored.

Statistical analysis used
One-way analysis of variance for unrelated samples when comparing the data of 3 studied groups and one-way analysis of variance for related samples when studying the dynamics of the indicator in each of the groups during 12 months of observation. Results are presented as mean ± standard deviation (M ± SD). Differences were considered significant at p&lt;0.05.