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

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℃ 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℃, the Vmax of succinate transport increased from 3.49±0.11 to 5.90±0.86 nmole/mg/5 sec for BBMV and from 2.86±0.25 to 3.63±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.