Intracellular recordings from supporting cells in the mammalian cochlea

Elizabeth Clark Oesterle, Purdue University

Abstract

The auditory receptor organ of the mammal, the organ of Corti, is constituted of a variety of different cell types. Several kinds of sensory cell are present along with a handful of support-cell types. Horseradish peroxidase marking, along with intracellular recording techniques, were utilized to examine whether the heterogeneity of support-cell type is reflected in the cells' electrical properties, and to determine the origin(s) of sound-induced potential changes recordable in the supporting cells of the organ. Recordings were made in the low-frequency region (3rd and 4th turns) of the adult guinea-pig cochlea, an in vivo preparation. Response characteristics of the support cells, to tone bursts at various sound levels, frequencies and durations, were compared to hair-cell responses (inner and outer hair cells) and potentials recorded in the organ-of-Corti fluid spaces. The support-cell response is composed of a number of components: an AC response at the frequency of the stimulating tone, harmonic components, a DC component present at the onset of the stimulating tone (termed the early-DC component), a slowly developing depolarization, and a slowly decaying afterpotential. Comparisons of responses from support cells, hair cells and organ-of-Corti fluids suggest that the AC, harmonic and early-DC components of the support-cell response are a reflection of hair-cell generated currents flowing across support-cell membranes. The slowly developing depolarization and slowly decaying afterpotential appear to emanate from the support cells themselves and are reminiscent of slow electrical potential changes that occur in glial cells. Differences are observed in the responses of the various support-cell types especially with respect to the slowly developing depolarization component.

Degree

Ph.D.

Advisors

Dallos, Purdue University.

Subject Area

Biology

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