Effect of Temperature on Dicarboxylate Transport in Plasma Membrane Vesicles of Rabbit Proximal Tubule

The temperature dependence of $Na^+-dependent$ succinate uptake was studied in brush border (BBMV) and basolateral (BLMV) membrane vesicles isolated from the rabbit kidney cortex. The succinate uptake was markedly altered by temperature in a similar fashion in both membranes. The temperature dependence was characterized by a nonlinear Arrhenius plot with a break point at 22 and $25^{\circ}C$ for BBMV and BLMV, respectively. The activation energy was 3.91 and 17.09 kcal/mole at above and below the break point respectively, far BBMV; 2.65 and 14.05 kcal/mole, respectively, for BLMV. When temperature increased f개m 20 to $35^{\circ}C$, the Vmax of succinate transport increased from $3.49{\pm}0.11\;to\;5.90{\pm}0.86\;nmole/mg/5\;sec$ for BBMV and from $2.86{\pm}0.25\;to\;3.63{\pm}0.32\;nmole/mg/5\;sec$ for BLMV, with no change in Km in both membranes. These results suggest that renal dicarboxylate transport is similarly sensitive to a change in membrane physical state in BBMV and BLMV.