AJP - Cell Physiology, Vol 263, Issue 5 C1088-C1095, Copyright © 1992 by American Physiological Society
Delayed shortening and shrinkage of cochlear outer hair cells
S. Ohnishi, M. Hara, M. Inoue, T. Yamashita, T. Kumazawa, A. Minato and C. Inagaki
Department of Pharmacology, Kansai Medical University, Osaka, Japan.
Slow shortening of cochlear outer hair cells has been speculated to modify
cochlear sensitivity. Tetanic electrical field stimulation of isolated
outer hair cells from guinea pigs shortened the cells for 2-3 min.
Electrical stimulation reduced cell length and volume (-13.5 +/- 1.5 and
-37.3 +/- 3.0% of initial values, respectively, n = 16) and decreased the
intracellular Cl- concentration. Cytochalasin B (100 microM) inhibited
electrical stimulation-induced shortening but not volume reduction. The
following chemicals or manipulations inhibited the responses: 10 microM
furosemide, 0.1 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS),
1 mM anthracene-9-carboxylic acid (AC9), 25 mM tetraethylammonium, 2.3
microM charybdotoxin (ChTX), 250 nM omega-conotoxin, and Ca(2+)-free
medium. These findings suggest that both electrical stimulation-induced
shortening and shrinkage of outer hair cells result not only from an
actin-mediated contractile force, but also from Cl- efflux through
furosemide-, DIDS-, and AC9-sensitive Cl- channels, and K+ efflux through
ChTX-sensitive K+ channels.
