Impedance spectroscopy: an accurate method of differentiating between viable and ischaemic or infarcted muscle tissue.

The object of the paper is to present results that show that impedance spectroscopy is an accurate method of assessing the condition of muscle tissue. Specimens of muscle tissue were excised from 36 Atlantic salmon and subjected to impedance spectroscopy measurements made at intervals during an 8h period of ischaemia and necrosis. These measurements were conducted for three different temperatures and for both the longitudinal and the transverse orientations of the muscle fibres. The specimens were also subjected to ATP, pH and visco-elastic measurement and analysis to establish the degree of correlation between changes in these quantities and impedance spectroscopy parameters due to ischaemia. It was concluded that the mean relaxation time, tau(c) was the impedance spectroscopy parameter that best described the changes taking place in the muscle tissue during the post-mortem period, decreasing by 60-76% during the 8h. This was the case for all three temperatures and for both orientations. Furthermore, the muscle tissue changes due to ischaemia, as reflected in the decrease in the mean relaxation time tau(c), were highly correlated with changes in the tissue ATP, pH and dynamic shear storage modulus G'.