Bioimpedance Changes in Rats with CCl4-Induced Liver Fibrosis

Abstract

To characterize the relationship between the stage of hepatic fibrosis and bioimpedance, several electric parameters were estimated in rats with <TEX>$CCl_4$</TEX>-induced liver fibrosis. Thirty three Sprague-Dawley rats were intraperitoneally injected with a <TEX>$CCl_4$</TEX>-mineral oil mixture (1:1, 0.2 mL/100 g) twice a week for 8 weeks. The resistance(R), reactance(X), impedance(Z), and dissipation factor(D) between 1 kHz and 100 kHz were then evaluated in the livers of the rats under pentobarbital anesthesia using an HP4294A Impedance Analyzer. The rats were killed 2, 4, 6, and 8 weeks later, and their livers were classified in accordance with Ishak's scoring system. R, X, and Z changed in accordance with the progression of hepatic fibrosis and the changes were greater at lower frequencies than at higher frequencies. In comparison, the D spectrum was biphasic; D increased initially then decreased with increasing frequency. All of the parameters(R, X, Z, and D) changed in accordance with the stage of fibrosis in the livers, but D changed specifically with the progression of fibrosis. These results indicate that hepatic fibrosis may be evaluated by determining the changes in D.