H2o2 activates red blood cell k-cl cotransport via stimulation of a
phosphatase.
Bize, Isabel, and Philip B. Dunham.
Department of Biology, Syracuse University, Syracuse, New York
13244
APStracts 2:0229C, 1995.
K-Cl cotransport is involved in volume regulation in a number of cell
types. Cell swelling stimulates K-Cl cotransport, probably by
inhibition of a volume-sensitive kinase. K-Cl cotransport can also be
activated by oxidants and thiol reagents. We investigated the effect
of H2O2 on K-Cl cotransport of LK sheep red cells in an attempt to
identify the target of oxidants. H2O2 stimulated K-Cl cotransportt;
The stimulation was virtually abolished by subsequent incubation with
calyculin, a protein phosphatase inhibitor. This suggests that H2O2
stimulates a calyculin-sensitive (CS)-phosphatase and activates K-Cl
cotransport by causing a decrease in phosphorylation of the
transporter or a regulatory protein. The thiol reagent NEM which
stimulates K-Cl cotransport, did not stimulate further in cells with
cotransport activated by staurosporine, but did stimulate cotransport
further in cells with cotransport activated by H2O2. These results
suggest that there are at least two distinct phosphorylation sites on
the transporter or a regulator. The results also suggest that the
phosphatase is associated with the membrane.
Received 2 November 1994; accepted in final form 12 April 1995.
APS Manuscript Number C655-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.