title: [Theoretical impedance analysis of the intact rat lens with an ellipsoidal shells model].
abstract: We measured a.c. admittances for isolated rat lenses over a wide frequency range of 100 Hz to 500 MHz. In order to evade electrode polarization at low frequencies, we examined extracted lenses by direct semi-squeezing with Pt black-coated platinum electrodes. This gave rise to a 10(6) increment in permittivity at low frequencies, and two distinct dielectric dispersions were exhibited; dispersion 1 with a characteristic frequency (fc) of 2 kHz, and dispersion 2 with an fc of 2 MHz. In terms of loss tangent function, the two dispersions clearly dominated as two peaks. By curve fitting analysis with an allocated ellipsoidal-shells model based on ultrastructural features of the lens with a lens equivalent circuit, dispersion 1 was assigned to the equatorial cortex where regularly arranged lens fibers ran parallel to the applied electric field, and dispersion 2 to the nucleus of complicated fibers, combined with the polar cortex where lens fibers ran perpendicular to the electric field. Our results suggested that both lens dispersions were beta-dispersions attributable to bio-membranes.
authors.affiliation: Department of Ophthalmology, Kochi Medical School, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Watanabe
authors.forename: R
authors.initials: R
authors.lastname: Matsuoka
authors.forename: K
authors.initials: K
authors.lastname: Seike
authors.forename: Y
authors.initials: Y
authors.lastname: Mokudai
authors.forename: H
authors.initials: H
authors.lastname: Ueno
mesh_terms: D000818:Animals; D017097:Electric Impedance; D066298:In Vitro Techniques; D007908:Lens, Crystalline / Q000502:physiology*; D008297:Male; D008433:Mathematics; D051381:Rats; D017208:Rats, Wistar