Changes in electrolyte concentrations alter the impedance during ischemia-reperfusion injury in rat brain

Abstract

Objective: Ischemic stroke is a major cause of death and disability worldwide. Nowadays, electrical impedance spectroscopy is an emerging tool to differentiate between normal and stroke conditions. Approach: In this study, changes in the bio-impedance spectroscopy using a two-electrode method with varying frequencies from 100 to 35 kHz have been assessed in a model of global cerebral ischemia in anesthetized rats during normal, occlusion and reperfusion conditions. Global cerebral ischemia was induced by bilateral common carotid artery occlusion for 40 min following 40 min of reperfusion. The concentration of sodium, potassium, calcium and chloride ions in the whole rat brain was determined by electrolyte analyzer. For the interpretation of in vivo results, changes in electrical impedance with varying concentrations of sodium, potassium and calcium ions in artificial cerebrospinal fluid (aCSF) were also observed using the bio-impedance spectroscopy method. Main results: The in vivo bio-impedance analysis suggests that the impedance is consistently increased during occlusion as compared to the normal condition. The in vitro study revealed that the impedance escalates with an increase in the concentration of potassium and calcium ions and reduces with an increase in the concentration of sodium ions in aCSF. A further electrolyte analysis suggested that the level of sodium and chloride ions is significantly decreased and the level of calcium and potassium is significantly increased during occlusion as compared to the normal condition. Significance: These findings suggest that the increase in impedance during occlusion may be due to changes in the ionic concentration of the rat brain. The above in vivo and in vitro studies successfully demonstrated and interrelated the change in impedance with corresponding changes in ionic concentration.

Assessment of Low Back Pain in Helicopter Pilots Using Electrical Bio-Impedance Technique: A Feasibility Study

“…Second, impedance information at low frequencies (<1 kHz) was not involved. In several studies it was found that impedance at low frequencies may be more sensitive to muscle state ( Kumar et al, 2019a ; Mortreux et al, 2019 ). Therefore, further studies on impedance measurement by sweeping frequency over a wide frequency range will be designed to investigate the specified dielectric parameters to assess LBP on the premise of rapid measurement and safety.…”

“…Nevertheless, the intrinsic physiological mechanism between LBP and impedance remained unclear since the microscopic morphology for different LBP scales was not measured. To date, several studies have investigated the influence of microscopic conditions of biological tissues on bioimpedance, such as the cell morphology ( Wang et al, 2015 ; Song et al, 2018 ) and electrolyte concentrations in biological tissues ( Kumar et al, 2019a , b ). Therefore, further work on intrinsic physiological mechanism will be performed in order to provide a solid biophysical fundamental to use EBI for early detection of LBP among helicopter pilots.…”

Análisis de impedancia bioeléctrica (AIB) en la producción animal. Revisión

“…Those membranes act as if they were a capacitor (Xc) (4) . This assessment is an indicator of body lean mass quantity, which can be related to the structure and function of cell membranes since each tissue component responds differently to the flow of an alternate applied current (18,19) .…”

Feasibility of Sectional Bioelectrical Impedance Spectrum Evaluating Joint Effusion in Rat

“…[12]. Therefore, in this paper, the sweep frequency measurement work in the frequency range 10 Hz-30 kHz, which may include α-dispersion and a part of β-dispersion [13].…”