Effects of extracellular atp on ion transport and intracellular
ca2+ in mongolian gerbil middle ear epithelium.
Furukawa, Masayuki, Katsuhisa Ikeda, Mutsuo Yamaya, Takeshi Oshima,
Hidetada Sasaki and Tomonori Takasaka.
Departments of Otorhinolaryngology and Geriatric Medicine, Tohoku
University School of Medicine, Sendai, Japan
APStracts 3:0356C, 1996.
The present study investigates the effects of ATP on ion transport and
Ca2+ mobilization in primary cultures of gerbil middle ear
epithelium. Extracellular ATP and other nucleotides elicited a
transient increase in Isc in a dose-dependent manner. The rank order
of potency in Isc responses corresponded with the sequence of the P2u
purinergic receptor when applied to the mucosal or the basolateral
side. Extracellular ATP induced a rise in the intracellular Ca2+
concentration ([Ca2+]i) in a dose-dependent manner. A similar rank
order of potency in the ATP-induced increases in [Ca2+]i was
observed. The time courses of the [Ca2+]i responses induced by ATP
closely paralleled those of the Isc responses. 1,2-Bis-(o
-aminophenoxy)ethane N,N,N,,N,-tetraacetic acid-acetoxymethyl ester
greatly reduced the increase in both the Isc and [Ca2+]i responses to
ATP. Diphenylamine-2-carboxylate, 4,4,-diisothiocyanostilbene-2,2,
-disulfonic acid, quinidine, and Ba2+ significantly blocked the ATP
-stimulated Isc. Glybenclamide had no effect on the ATP-stimulated
Isc. These results are consistent with the hypothesis that
extracellular ATP and other nucleotides induce Cl- secretion across
the apical membrane in cultured gerbil middle ear epithelium by
activation of the apical Cl- channels via multiple modes of
regulation.
Received 23 July 1996; accepted in final form 8 October 1996.
APS Manuscript Number C408-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 November 1996