Na+,K(+)-ATPase activity in the cochlear lateral wall of the gerbil.
We examined Na+,K(+)-ATPase activity in four regions of the gerbil cochlear lateral wall by measuring intracellular Na+ concentration ([Na+]i). The application of 1 mM ouabain and removal of external K+ caused a most striking increase in [Na+]i of the suprastrial fibrocytes, followed by the stria vascularis and the type II fibrocytes, but no detectable response in the type I fibrocytes. These results may imply the potency of the Na+,K(+)-ATPase activity. The high values of the resting [Na+]i in these cells under perilymph-like solution returned to the [Na+]i within physiological values after exposure to low-Na+ conditions similar to endolymph. Our results are interpreted in the light of recent morphological findings with regard to the roles in the secretion of K+ into endolymph of several cell types within the lateral wall.
Furukawa
M
M
Department of Otolaryngology, Tohoku University School of Medicine, Sendai, Japan. furukawa@orl.med.tohoku.ac.jp
Ikeda
K
K
Takeuchi
S
S
Oshima
T
T
Kikuchi
T
T
Takasaka
T
T
D000818:Animals; D001572:Benzofurans; D001692:Biological Transport / Q000502:physiology; D003051:Cochlea / Q000737:chemistry / Q000166:cytology / Q000201:enzymology*; D004710:Endolymph / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004988:Ethers, Cyclic; D005456:Fluorescent Dyes; D005849:Gerbillinae; D007150:Immunohistochemistry; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis / Q000378:metabolism*
D001572:Benzofurans; D004791:Enzyme Inhibitors; D004988:Ethers, Cyclic; D005456:Fluorescent Dyes; C061665:sodium-binding benzofuran isophthalate; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium