Ionic currents and current-clamp depolarisations of type I and type II hair cells from the developing rat utricle
| Autor: | A. Steinacker, G. W. T. Lennan, Alain Sans, J. Lehouelleur |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
medicine.medical_specialty
Patch-Clamp Techniques Physiology Voltage clamp Clinical Biochemistry Population In Vitro Techniques Ion Channels Sodium Channels Membrane Potentials chemistry.chemical_compound Physiology (medical) Current clamp Internal medicine Hair Cells Auditory medicine Animals 4-Aminopyridine Saccule and Utricle education education.field_of_study Tetraethylammonium Inward-rectifier potassium ion channel Conductance Rats Electrophysiology Endocrinology chemistry Biophysics Algorithms Type II Hair Cell |
| Zdroj: | Pfl�gers Archiv European Journal of Physiology. 438:40-46 |
| ISSN: | 1432-2013 0031-6768 |
| DOI: | 10.1007/s004240050877 |
| Popis: | Ionic currents and the voltage response to injected currents were studied in an acutely dissected preparation of the rat utricle between birth and postnatal day 12 (PN12). Based upon morphological criteria, the sensory cells examined were divided into two classes, "type I" and "type 2 category," the latter of which may include some immature type I cells. The former group comprises a clearly defined electrophysiological population, with one large outwardly rectifying potassium conductance that is sensitive to 4-aminopyridine (4-AP), insensitive to tetraethylammonium (TEA) and displays voltage-dependent activation kinetics. In the absence of enzymatic dissociation procedures, and with the epithelium left largely intact, the mean half activation of this conductance was -30.3 mV at PN3, and -37.5 mV at PN12. At both stages it was almost entirely turned off at -74 mV. Omission of ATP from the intracellular solution appeared to prevent rundown of this conductance. Type II category hair cells formed a more heterogeneous population, exhibiting a distinct TEA-sensitive delayed rectifier potassium conductance; the rapidly activating and inactivating IA; an inward rectifier; and inward sodium currents at around PN3. Both cell types depolarised strongly in response to injected currents, with time courses reflecting the activation kinetics of their major outward conductances. |
| Databáze: | OpenAIRE |
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