AJP - Cell Physiology, Vol 254, Issue 2 C286-C296, Copyright © 1988 by American Physiological Society
Volume response of quiescent and interleukin 2-stimulated T-lymphocytes to hypotonicity
S. C. Lee, M. Price, M. B. Prystowsky and C. Deutsch
Department of Physiology, University of Pennsylvania, Philadelphia 19104-6085.
Regulatory volume decreased (RVD) in lymphocytes in response to
hyptonically induced swelling is dependent on the membrane permeabilities
of K+, Cl-, and H2O. We used electronic cell sizing, cell water
determination, and the whole cell patch-clamp method to study these
membrane permeabilities in the cloned mouse T-lymphocyte, L2. Quiescent L2
cells express low levels of a voltage-gated K+ channel and show no RVD at
25 degrees C. In contrast, L2 cells stimulated to proliferate with the
growth factor interleukin 2 have increased K+ conductance and show RVD in
response to hypotonicity. RVD in stimulated cells is blocked by quinine and
verapamil at levels that also completely block the voltage-gated K+
conductance. Swollen, unstimulated L2 cells can be induced to shrink by
addition of the monovalent cation ionophore gramicidin in the presence of
impermeant extracellular organic cations; gramicidin also enhances the rate
of RVD in stimulated cells. Additionally, the anion transport inhibitor
4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) blocks this
gramicidin-facilitated RVD. These results suggest that a minimum requisite
Cl- permeability is present even in the unstimulated L2 cells, that a
necessary and limiting K+ permeability determines the rate of RVD, and that
this K+ permeability increases after growth-factor stimulation as predicted
from the direct measurement of voltage-gated K+ conductance. The hydraulic
permeability is approximately 70% greater in proliferating L2 cells than in
quiescent cells. At 37 degrees C, some RVD occurs in unstimulated L2 cells,
and stimulated cells show faster and more complete shrinkage. These results
are discussed with respect to the underlying membrane permeabilities and
their relation to stimulated cell proliferation.
