Isolation of and Calcium Kinetics in Cochlear Inner Hair Cells of the Guinea Pig

Abstract

Single inner hair cells of the guinea pig cochlea were isolated using enzymatic and mechanical techniques. the intracellular free calcium ion concentrations ([Ca²⁺]i) of the isolated inner hair cells were determined using the Ca²⁺ sensitive dye fura-2 and digital imaging microscopy. in the presence of 1 um ionomycin, a Ca²⁺ ionophore, there was an irreversible increase in [Ca²⁺]i. the 150 mM KC1 stimulation, which induces a depolarization, resulted in a temporary increase in [Ca²⁺]i. This increase in [Ca²⁺]i was not observed under conditions of depolarization, in Ca²⁺-free medium. These observations are interpreted to mean that the increased [Ca²⁺]i during membrane depolarization mainly originates from an influx of extracellular Ca²⁺ into the cytoplasm.

Key Words:

• cochlea
• isolated inner hair cells
• intra-cellular free Ca²⁺
• digital imaging microscopy
• guinea pig