Development of K+ and Na+ conductances in rodent postnatal semicircular canal type I hair cells

Li, Gang Q.; Meredith, Frances L.; Rennie, Katherine J.

doi:10.1152/ajpregu.00460.2009

Cited by 22 publications

(30 citation statements)

References 35 publications

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“…5 a). The HVA K + current was present at potentials above approximately -55 mV, as previously described [Rüsch and Eatock, 1996;Li et al, 2010], and outward currents in immature HCI were reduced at all voltage steps following neomycin exposure ( fig. 5 b).…”

Section: Ag Reduce Hva K + Currents In Immature Hcisupporting

confidence: 73%

“…Gerbil ages ranged from postnatal day (P)5-66 and we considered hair cells from animals aged P25 and older to be mature [Li et al, 2010]. Gerbils were injected with pentobarbital sodium (Nembutal; 50 mg/kg, intraperitoneally) and ketamine (10 mg/kg, intramuscularly).…”

Section: Preparation Of Vestibular Tissuementioning

confidence: 99%

“…In gerbil semicircular canal hair cells, the LVA K + current begins to appear in HCI during the first few postnatal days and its expression is preceded by the HVA K + current. By the third postnatal week, all morphologically identified HCI express the LVA K + current [Li et al, 2010]. To determine if AG blocked HCI membrane currents before the appearance of the LVA K + current, HCI were isolated from gerbil cristae at ages P5-9.…”

Section: Ag Reduce Hva K + Currents In Immature Hcimentioning

confidence: 99%

“…A high-voltage-activated (HVA) K + current with a voltage of half-maximal activation of approximately -30 mV is present in immature hair cells during the first postnatal week [Rüsch et al, 1998;Géléoc et al, 2004;Hurley et al, 2006]. A low-voltage-activated (LVA) K + current (voltage of half-maximal activation more negative than -60 mV) is absent during the first few postnatal days in rat and gerbil HCI, but expressed in all HCI by the third postnatal week [Hurley et al, 2006;Li et al, 2010]. The molecular identity of the K + channels underlying the macroscopic K + conductance is unclear but may include contributions from delayed-rectifier, erg and KCNQ4 channels [Kharkovets et al, 2000;Hurley et al, 2006;Holt et al, 2007].…”

Section: Introductionmentioning

confidence: 99%

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Inhibition of K+ Currents in Type I Vestibular Hair Cells by Gentamicin and Neomycin

Mann¹,

Johnson²,

Meredith³

et al. 2013

Audiol Neurotol

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Significant ototoxicity limits the use of aminoglycoside (AG) antibiotics. Several mechanisms may contribute to the death of both auditory and vestibular hair cells. In this study the effects of gentamicin and neomycin on K⁺ currents in mature and early postnatal type I vestibular hair cells (HCI) were tested directly. The whole-cell patch clamp technique was used to assess the effects of AG and KCNQ channel modulators on K⁺ currents (I_K) in HCI acutely isolated from gerbil semicircular canals. Extracellular neomycin (1 mM) rapidly reduced peak outward I_K by 16 ± 4% (n = 9) in mature HCI (postnatal days, P, 25-66). Gentamicin (5 mM) reduced outward I_K by 16 ± 3% (n = 8). A similar reduction in outward current was seen in immature HCI (P5-9) that lacked the low-voltage-activated component of I_K observed in mature cells. Intracellular application of gentamicin and neomycin also reduced I_K in mature HCI. Modulators of KCNQ channels were used to probe KCNQ channel involvement. The selective KCNQ antagonist XE991 did not reduce I_K and the neomycin-induced reduction in I_K was not reversed by the KCNQ agonist flupirtine. Application of intracellular poly-D-lysine to sequester PIP₂ did not reduce I_K. Application of the K⁺ channel blocker 4-aminopyridine (4-AP) strongly reduced I_K, and extracellular AG in the presence of 4-AP gave no further inhibition of I_K. In summary, AG significantly reduce the 4-AP-sensitive I_K in early postnatal and mature HCI. K⁺ current inhibition differs from that seen in outer hair cells, since it does not appear to involve PIP₂ sequestration or KCNQ channels.

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Section: Ag Reduce Hva K + Currents In Immature Hcisupporting

confidence: 73%

Section: Preparation Of Vestibular Tissuementioning

confidence: 99%

Section: Ag Reduce Hva K + Currents In Immature Hcimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Inhibition of K+ Currents in Type I Vestibular Hair Cells by Gentamicin and Neomycin

Mann¹,

Johnson²,

Meredith³

et al. 2013

Audiol Neurotol

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“…We did not see the mixed Ca 2+ -Na + spikes that are typical of mouse IHCs in the first postnatal week (Marcotti et al, 2003b). All Atoh1 + cells lacked the voltage-gated Na + currents of immature HC subtypes (Chabbert et al, 2003;Eckrich et al, 2012;Géléoc et al, 2004;Li et al, 2010;Marcotti et al, 2003b;Oliver et al, 1997;Witt et al, 1994;Wooltorton et al, 2007). Again, these channels either were never expressed or had stopped being expressed by the earliest time point we examined, 12 days of in vitro differentiation.…”

Section: Voltage-gated Currents In Differentiated Hair Cell-like Cellsmentioning

confidence: 73%

Distinct capacity for differentiation to inner ear cell types by progenitor cells of the cochlea and vestibular organs

McLean

Eatock

et al. 2016

Development

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Disorders of hearing and balance are most commonly associated with damage to cochlear and vestibular hair cells or neurons. Although these cells are not capable of spontaneous regeneration, progenitor cells in the hearing and balance organs of the neonatal mammalian inner ear have the capacity to generate new hair cells after damage. To investigate whether these cells are restricted in their differentiation capacity, we assessed the phenotypes of differentiated progenitor cells isolated from three compartments of the mouse inner ear -the vestibular and cochlear sensory epithelia and the spiral ganglion -by measuring electrophysiological properties and gene expression. Lgr5 + progenitor cells from the sensory epithelia gave rise to hair cell-like cells, but not neurons or glial cells. Newly created hair cell-like cells had hair bundle proteins, synaptic proteins and membrane proteins characteristic of the compartment of origin. PLP1 + glial cells from the spiral ganglion were identified as neural progenitors, which gave rise to neurons, astrocytes and oligodendrocytes, but not hair cells. Thus, distinct progenitor populations from the neonatal inner ear differentiate to cell types associated with their organ of origin.

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Postnatal Expression of an Apamin-Sensitive K(Ca) Current in Vestibular Calyx Terminals

Meredith

Rennie

2011

J Membrane Biol

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Afferent innervation patterns in the vestibular periphery are complex and vestibular afferents show a large variation in their regularity of firing. Calyx fibers terminate on type I vestibular hair cells and have firing characteristics distinct from bouton fibers that innervate type II hair cells. Whole cell patch clamp was used to investigate ionic currents that could influence firing patterns in calyx terminals. Underlying K(Ca) conductances have been described in vestibular ganglion cells, but their presence in afferent terminals has not been investigated previously. Apamin, a selective blocker of SK-type calcium-activated K+ channels, was tested on calyx afferent terminals isolated from gerbil semicircular canals during postnatal days 1 to 50. Lowering extracellular calcium or application of apamin (20–500 nM) reduced slowly activating outward currents in voltage clamp. Apamin also reduced the action potential after-hyperpolarization (AHP) in whole cell current clamp, but only after the first two postnatal weeks. K+ channel expression increased during the first postnatal month and SK channels were found to contribute to the AHP, which may in turn influence discharge regularity in calyx vestibular afferents.

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Development of K⁺ and Na⁺ conductances in rodent postnatal semicircular canal type I hair cells

Abstract: Li GQ, Meredith FL, Rennie KJ. Development of K ϩ and Na ϩ conductances in rodent postnatal semicircular canal type I hair cells.

Cited by 22 publications

References 35 publications

Inhibition of K<sup>+</sup> Currents in Type I Vestibular Hair Cells by Gentamicin and Neomycin

Inhibition of K<sup>+</sup> Currents in Type I Vestibular Hair Cells by Gentamicin and Neomycin

Distinct capacity for differentiation to inner ear cell types by progenitor cells of the cochlea and vestibular organs

Postnatal Expression of an Apamin-Sensitive K(Ca) Current in Vestibular Calyx Terminals

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