Electrical impedance spectroscopy of young and old mouse multiple tissues

Elucidating alterations in the electrophysiological properties of biological tissues during aging is crucial for understanding the mechanisms of tissue aging and developing early diagnostic strategies.Electrochemical Impedance Spectroscopy (EIS) serves as a robust tool for characterizing tissue electrical properties. However, the systematic and quantitative effects of age and frequency on complex impedance parameters-such as magnitude (Z), resistance (R), and reactance (X)-across multiple tissues remain inadequately explored. In this study, we applied EIS to systematically profile the complex impedance spectra of ten major tissues from 2-and 18-month-old male and female mice, including skin, brain, spleen, heart, lung, liver, kidney, muscle, testis, and adipose tissue, over a frequency range of 20 Hz to 1 MHz. Our results indicate that aging significantly alters key impedance parameters (Z, R, and X) of skin, muscle, adipose, and liver tissue in a frequency-dependent manner, whereas other tissues exhibited minimal age-related changes. Using Nonlinear least-squares regression algorithms, we elucidated the complex, nonlinear relationships among frequency, age, and impedance parameters, establishing highly accurate predictive models, particularly for organs showing pronounced changes. The derived fitting equations effectively captured essential features of the impedance spectra. This study quantitatively reveals the significant influence of age and frequency on impedance parameters in specific tissues, providing new insights into the electrophysiological basis of tissue aging and highlighting the potential of EIS as a rapid biophysical tool for detecting biological aging.