M. Oike et al., THE VOLUME-ACTIVATED CHLORIDE CURRENT IN HUMAN ENDOTHELIAL-CELLS DEPENDS ON INTRACELLULAR ATP, Pflugers Archiv, 427(1-2), 1994, pp. 184-186
We have studied the effect of intracellular ATP on volume-activated Cl
--currents in endothelial cells from human umbilical veins by means of
the whole-cell patch-clamp technique. The run-down of this current in
ruptured patches during repetitive applications of hypotonic solution
s (HTS) could be significantly reduced if the cells were internally pe
rfused with a pipette solution that contained 4 mmol/l ATP. This run-d
own was much less pronounced if currents were recorded using nystatin-
perforated patches. The amplitude of the current was drastically reduc
ed and its activation became slower if the cells were superfused with
a glucose-free medium with 1 mmol/l KCN. Adding 4 mmol/l ATP gamma S,
a poorly hydrolyzable ATP-analogue, to the patch pipette prevented run
down of the current during repetitive activations by HTS, even if the
cells were superfused with glucose-free solution with 1 mmol/l KCN. It
is concluded that activation of the mechanosensitive Cl- conductance
in human endothelial cells requires the presence of intracellular ATP,
but not its hydrolysis.