AJP - Renal Physiology, Vol 245, Issue 6 778-F783, Copyright © 1983 by American Physiological Society
Furosemide-sensitive thallium fluxes in smooth muscle of rabbit uterus
A. Johns and S. V. Cutshaw
The furosemide-sensitive uptake of thallium represents approximately equal
to 50% of the total uptake of thallium by rabbit uterus and requires Cl-
and Na+. The furosemide-sensitive uptake of thallium is stimulated by other
ions at low concentrations with the rank order Li+ greater than Tl+ greater
than K+ = Rb+ greater than Cs+ and is inhibited by these ions at high
concentrations with the rank order Tl+ greater than K+ = Rb+ greater than
Cs+ greater than Li+, suggesting multiple cation binding sites on the
carrier. Uptake of 36Cl- is inhibited by furosemide in the presence of
ouabain. Thallium efflux and 36Cl efflux in the presence of ouabain is
inhibited by furosemide. The chloride concentration regulates the
proportion of thallium uptake that is ouabain sensitive and furosemide
sensitive without altering the total uptake. It is suggested that the
furosemide-sensitive uptake of thallium reflects a Na+-Cl- -K+ exchange
system that could be classified as a cotransport or countertransport of any
two of these ions and also could be the smooth muscle chloride pump.
