Effects of Sodium or Glucose Exclusion from the Incubation Medium on Drug Transfer across Rat Jejunal Membrane in Vitro : An Electrophysiological Study

Abstract

The effects of buffer components, glucose and sodium, on the passive transfer of sulfanilic acid (SA) and sulfaguanidine (SG) across isolated rat jejunal membranes were investigated, together with their effects on the transmural potential difference. (PD) and the membrane resistance (R_m). Glucose or sodium exclusion from bathing solutions significantly increased the mucosal-to-serosal transfer of both drugs. Glucose exclusion caused an irreversible reduction in PD, and the active transfer of L-phenylalanine (L-Phe) was also inhibited. However, effects of sodium exclusion on PD and the transfer of SA were reversible. The addition of phloridzin (Phl) to the mucosal solution induced the effect similar to that of glucose exclusion. In contrast, R_m was not significantly altered by the exclusion of glucose or the addition of Phl. It is clear that environmental conditions which reduce the active transport activity of the membrane enhance the membrane permeability to drugs.