Journal
JOURNAL OF PHYSIOLOGY-LONDON
Volume 548, Issue 2, Pages 383-400Publisher
WILEY
DOI: 10.1113/jphysiol.2002.034801
Keywords
-
Categories
Ask authors/readers for more resources
Developmental changes in electrophysiological membrane properties of mouse cochlear inner hair cells (IHCs)were studied from just after terminal differentiation up to functional maturity. As early as embryonic day 14.5 (E14.5) newly differentiated IHCs express a very small outward K+ current that is largely insensitive to 4-aminopyridine (4-AP). One day later the inward rectifier, I-Kl, is first observed. These immature cells initially exhibit only slow graded voltage responses under current clamp. From E17.5 spontaneous action potentials occur. During the first week of postnatal development, the outward K+ current steadily increases in size and a progressively larger fraction of the current is sensitive to 4-AP. During the second postnatal week, the activation of the 4-AP-sensitive current, by now contributing about half of the outward K+ current, shifts in the hyperpolarizing direction. Together with an increase in size of I-Kl, this hyperpolarizes the cell, thus inhibiting the spontaneous spike activity, although spikes could still be evoked upon depolarizing current injection. Starting at about the onset of hearing (postnatal day 12, P12) immature IHCs make the final steps towards fully functional sensory receptors with fast graded voltage responses. This is achieved mainly by the expression of the large-conductance Ca2+-activated K+ current I-K,I-f, but also of a current indistinguishable from the negatively activating I-K,I-n previously described in mature outer hair cells (OHCs). The 4-AP-sensitive current continues to increase after the onset of hearing to form the major part of the mature delayed rectifier, I-K,I-s. By P20 IHCs appear mature in terms of their complement of K+ conductances.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available