Simultaneous determination of anions in nanoliter volumes.

Background: The study of renal tubular transport requires the ability to accurately measure ion concentrations in samples taken from single tubules. Sample collection and analysis are laborious, so methods allowing determination of multiple ion species in a small volume sample are advantageous. This article describes a method for the simultaneous analysis of anions at physiologic concentrations in nanoliter volumes of tubular fluid.

The natriuretic effect of glibenclamide: evidence for a non-luminal site of action.

Inhibition of sodium reabsorption in the loop of Henle (LOH) contributes to the natriuretic effect of systemically administered glibenclamide. Although it has been suggested that the underlying mechanism involves inhibition of low-conductance potassium channels in the apical membrane of the thick ascending limb, these channels are relatively insensitive to glibenclamide ( K(i) ~200 micro M). In the present study we used capillary electrophoresis techniques to determine plasma and tubular fluid concentrations of glibenclamide in anaesthetised, glibenclamide-infused rats during maximal natriuresis.