Abstract
In order to study the characteristics of oxalate transport across the brush border membrane, we studied oxalate uptake by rat renal cortical brush border membrane vesicles (BBMV). Vesicles were prepared with MgCl2 precipitation method and oxalate was measured by a modification of the millipore filtration technique, Transport of oxalate by these vesicles was non-saturable under the condition of salt and anion free medium indicating passive diffusion, The maximum uptake in BBMV at 30°C was obtained at 10 min incubation. Low temperature experiments showed gradual increase of oxalate accumulation into BBMV up to 90mine The rate of oxalate transport by the vesicles was decreased by the presence of both the Na and K gradient (in<out). The extravesicular Cl ion stimulated the accumulation of oxalate into BBMV significantly. The hypotonic lysis indicated the temperature dependent efflux of oxalate from osmotically sensitive intra vesicular space. The existence of extravesicular 5 mM paraaminohippurate (PAH) decreased oxalate uptake in BBMV and inhibited the efflux of oxalate from BBMV significantly.
