DIELECTRIC POLARIZATION OF ANIMAL LUNG AT RADIO FREQUENCIES.

Dielectric properties of the inflated and deflated feline lung were investigated in vivo at frequencies from 10 kHz to 100 MHz. A computer-controlled network analyzer and a multiring capacitive sensor were used. It was found that, in the frequency range investigated, both the dielectric constant and the conductivity of the deflated lung were higher than those of the inflated one. The analysis of the experimental data was performed using two approaches: the loss-tangent method, and the curve-fitting computer program called STEPIT. It was found that in the middle band of frequencies for both inflated and deflated states of the lung, the dielectric response mainly reflects the membrane polarization of the capillary erythrocytes with possible contributions of other components, e. g. , the pulmonary microphages. The dielectric relaxation time for the capillary erythrocytes in the lung is similar to that for the packed cells, which is much longer than for the erythrocytes at physiological concentrations. The dielectric parameters at low frequencies obtained using the STEPIT program differ significantly between the inflated and deflated lung.