The Lateral Walls of Inner and Outer Hair Cells

Forge, Andrew

doi:10.1007/978-1-4684-5640-0_4

Cited by 9 publications

(5 citation statements)

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“…7) showed relatively few dispersed intramembrane particles (IMP) whereas IMP were densely packed on the lateral plasma membrane (Fig. 9) as previously reported for pre-fixed material (Forge, 1986(Forge, , 1989Forge et al, 1988). However, the E-face of the apical membrane (Fig.…”

Section: Assessment Of the Preparative Proceduressupporting

confidence: 78%

“…To assess possible peculiarities related exclusively to the use of unfixed tissue or any particular artefacts associated with fracturing such material, the membrane fracture faces were examined in detail to compare with the features seen in previous studies of fixed, glycerinated tissue (Forge 1986(Forge , 1987(Forge , 1989Forge et al, 1988). The P-faces of the stereocilia (Fig.…”

Section: Assessment Of the Preparative Proceduresmentioning

confidence: 99%

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Assessment of ultrastructure in isolated cochlear hair cells using a procedure for rapid freezing before freeze-fracture and deep-etching

1991

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Separated cochlear outer hair cells and isolated strips of organ of Corti containing hair cells and supporting cells have been rapidly frozen before freeze-fracture and deep-etching by immersion of samples sandwiched between two copper plates into liquid nitrogen-cooled propane: isopentane. Assessment of this procedure has shown that no significant freezing damage occurs. The ultrastructure of the hair cells revealed by freeze-fracture of these non-chemically fixed preparations was generally very similar to that seen in fixed material. This indicates that the processing of cochlear tissue normally used for electron microscopy produces few obvious structural artefacts. It also demonstrated that procedures for isolating cochlear hair cells generally do not affect cell structure significantly. However, some isolated hair cells did show abnormalities within the membranes of the lateral cisternae. Such membrane alterations, which would not be identified by light microscopy, occurred to a variable extent but were more commonly present after prolonged periods in maintenance medium. Deep-etching of the preparations to examine extracellular features around stereocilia revealed clearly lateral cross-links between stereocilia. However, tip-links could not be positively identified in either unfixed or prefixed preparations.

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Section: Assessment Of the Preparative Proceduressupporting

confidence: 78%

Section: Assessment Of the Preparative Proceduresmentioning

confidence: 99%

Assessment of ultrastructure in isolated cochlear hair cells using a procedure for rapid freezing before freeze-fracture and deep-etching

1991

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“…Much larger local rises in Ca2+ would occur if the Ca2+ enters a restricted volume of the cell. An upper bound for the current would be obtained if the Ca2+ was contained within the 50 nm space immediately subjacent to the plasma membrane delimited by the cisternae (Saito, 1983;Forge, 1989) and expected to form a natural diffusion barrier. In that case the rise of Ca2+ in that space would have been 100 times larger and large enough to activate a variety of cytoskeletal processes which require pCa to fall below 6.…”

Section: Calcium Buffering Within Outer Hair Cellsmentioning

confidence: 99%

Control of intracellular calcium by ATP in isolated outer hair cells of the guinea‐pig cochlea.

Ashmore

Ohmori

1990

The Journal of Physiology

165

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SUMMARY1. Intracellular calcium levels were monitored in isolated outer hair cells of the guinea-pig cochlea using the calcium-sensitive dye Fura-2.2. The calcium in the cells was studied during application of ATP externally applied from a pipette. ATP induced a rise of intracellular calcium which could be separated into two components: a rapid rise, peaking in 20 s, localized around the apical end of the cell, and a slower rise, peaking in 50-150 s but spread throughout the cell. The effects were observed with 5, 25 and 100 jtM-ATP concentrations.3. In the absence of external Ca2", ATP was still able to trigger a rise in Ca2", but with a longer delay. Under these conditions, the cells did not show the initial rapid Ca2+ rise. The result suggests that ATP can mobilize intracellular stores.4. A rise in intracellular Ca21 was also observed when 5 mM-caffeine was applied to the bath.5. Simultaneous measurements were made of whole-cell currents and intracellular calcium. ATP activated an inward current at resting potentials of -60 mV. Internal Ca21 levels increased during the inward current. In current-clamped cells Ca2+ levels also increased during the associated depolarization produced by ATP.6. Adenosine (150/,M) did not produce any measurable inward current. Acetylcholine (ACh, 100 ,tM-1 mM) produced only a small rise in Ca2+. However, applied simultaneously with ATP, ACh suppressed the rise in intracellular Ca2+ produced by ATP, with the kinetics of a competitive antagonist.7. Intracellular Ca2+ increased with step depolarizations of the cell above -20 mV during whole-cell clamp. Large rises in Ca2+ were also observed on depolarizing the cell with isotonic KC1.8. Calcium levels in supporting cells of the organ of Corti were sensitive to ATP. In these cells, rises in intracellular Ca2+ did not require the presence of extracellular c2+.

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“…There have been a number of reports in deep-etched basolateral membranes of dense arrays of particles in the outer hair cell basolateral membrane (Forge, 1989;Kalinec, Holley, Iwasa, Lim & Kachar, 1992). These particle densities are estimated to be about 3000 ,tm'2, or comparable to those charge densities suggested by the electrophysiology.…”

Section: Gating Charge Movementsmentioning

confidence: 81%

Untitled

1994

Experimental Physiology

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The Lateral Walls of Inner and Outer Hair Cells

Cited by 9 publications

References 5 publications

Assessment of ultrastructure in isolated cochlear hair cells using a procedure for rapid freezing before freeze-fracture and deep-etching

Assessment of ultrastructure in isolated cochlear hair cells using a procedure for rapid freezing before freeze-fracture and deep-etching

Control of intracellular calcium by ATP in isolated outer hair cells of the guinea‐pig cochlea.

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