The first observation of osmotically neutral sodium accumulation in the myocardial interstitium

I Artyukov,R Feshchenko,M Fratini,A Gianoncelli,G Arutyunov,I Bukreeva,V Mitrokhin,M Bobrov,A Sokolova,A Cedola,A Vinogradov,D Dragunov

doi:10.1038/s41598-021-01443-8

Abstract

The aim of this study was the detection and quantification of the Na+ depositions in the extracellular matrix of myocardial tissue, which are suggested to be bound by negatively charged glycosaminoglycan (GAG) structures. The presented experimental results are based on high resolution X-ray fluorescence (XRF) spectromicroscopy technique used to perform a comparative analysis of sodium containment in intracellular and interstitial spaces of cardiac tissues taken from animals selected by low and high sodium intake rates. The experimental results obtained show that high sodium daily intake can result in a remarkable increase of sodium content in the myocardial interstitium.

Highlights

The aim of this study was the detection and quantification of the Na+ depositions in the extracellular matrix of myocardial tissue, which are suggested to be bound by negatively charged glycosaminoglycan (GAG) structures
The samples of cardiac muscle tissues of rats were studied by means of 3 techniques: histology analysis, synchrotron radiation based X-ray transmission microscopy (STXM) and X-ray fluorescent microscopy (XFM) using the same spatial resolution of about 1 μm
The histological analysis of the tissues taken from high sodium diet animals revealed several interstitial lymphocytes, degranulated mast cells, macrophages, fibroblasts as well as perivascular edema of the interstitium

Summary

Introduction

The aim of this study was the detection and quantification of the Na+ depositions in the extracellular matrix of myocardial tissue, which are suggested to be bound by negatively charged glycosaminoglycan (GAG) structures. In 2007–2011 in the framework of the MARS-500 program[10], a prolonged and accurate study on human sodium intake/excretion ratio has discovered that amounts of excreted sodium are not related directly to the sodium intake and arterial pressure values. This fact was explained by the existence of osmotically passive sodium deposits in skin and muscle tissues that have been formed earlier under conditions of high sodium diet and made their contribution to the elevated level of sodium in the urine. Several MRI studies leading to the conclusion, that the heart is a part of the body’s sodium storage (see, for example14) and showing a link between sodium intake and left ventricular hypertrophy[15]

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