Osmosensitivity of the hyperpolarization-activated chloride current
in human intestinal t84 cells.
Fritsch, Janine, and Aleksander Edelman.
Laboratoire du Calcium et Tissu Osseux dans l'organisme en
d[acute]eveloppement, CNRS URA 583, H[circumflex]opital des Enfants
Malades, 75015 Paris, France and Laboratoire de Physiologie et
Biophysique des Syst[grave]emes de Transport, INSERM U. 323, C.H.U.
Necker, 75015 Paris, France
APStracts 3:0330C, 1996.
The osmosensitivity of the hyperpolarization-activated chloride
current, (IClhyp), in T84 cells was studied using the whole cell
patch-clamp recording configuration. Hypotonicity is known to
activate an outwardly rectifying Cl- current (HIORC) distinct from
IClhyp, in these cells. The differing sensitivities of HIORC and
IClhyp towards inhibitors (1.9 dideoxyforskolin blocked HIORC but not
IClhyp, and Cd2+ inhibited IClhyp but not HIORC) allowed us to
investigate the osmoregulation of IClhyp. Hypotonicity induced an
increase in IClhyp amplitude. Protein phosphatases inhibitors
prevented this effect and hypotonic solutions became slightly
inhibitory. Hypertonicity resulted in a transient increase in IClhyp
amplitude followed by a large decrease. The complex responses of
IClhyp to osmotic changes indicate that these signals affect the same
channel via multiple transduction pathways. The responses of IClhyp
to hypotonicity features in common with the responses of ClC-2
channels expressed in Xenopus oocytes (activation) and with
hyperpolarization-activated chloride currents in other cell types,
such as osteoblasts and mandibular duct cells (inhibition).
Received 19 June 1996; accepted in final form 11 October 1996.
APS Manuscript Number C350-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996