Substrate Modulation of Fatty Acid Effects on Energization and Respiration of Kidney Proximal Tubules during Hypoxia/Reoxygenation (original) (raw)
Figure 8
Support of energization by succinate compared to complex I substrates after H/R in rabbit and mouse tubules.
Tubules were subjected to either normoxic incubation or to 67.5(Rabbit, Panels A, C, and D) or 30 min. hypoxia (Mouse, panels, B, E, and F) followed by 60 min reoxygenation then measurement of energization using safranin O uptake with either succinate (S) glutamate+malate (GM), α-ketoglutarate+malate (AM) or α-ketoglutarate+malate+glutamate. Succinate was also studied with addition of either glutamate (SG), rotenone (1 µM, SR) or both glutamate and rotenone (SGR). Measurements were made initially without delipidated albumin (dBSA) followed by its addition (0.5 mg/ml) at the vertical marks in the tracings. Group averages±SEM for N = 5 for both rabbit and mouse are summarized in panels A and B. Typical tracings are shown in panels C–F. Statistics shown in panels A and B indicate values significantly different from the corresponding S group for the succinate studies or AM group for the complex I substrate studies at either *P<0.05, #P<0.01, or +P<0.001. Other statistical analysis indicated that all H/R conditions were significantly different (P<0.01) from the corresponding normoxic conditions except for the rabbit SG, SR and SGR groups with dBSA, which completely recovered. dBSA significantly increased energization (P<0.01) in all rabbit studies except for the normoxic succinate groups. In the mouse tubules, dBSA significantly improved energization of normoxic tubules with AM (P<0.05) and in all hypoxic groups (P<0.01) except for SR and SGR. In both normoxic and hypoxic rabbit tubules, energization with complex I substrates was poorer than with succinate (P<0.05) except for normoxic tubules in the presence of dBSA. In normoxic mouse tubules, complex I supported energization did not differ from succinate, but after H/R complex I rates energization was better than with succinate alone irrespective of the presence of dBSA (P<0.05). Relative to the other succinate conditions, complex I energization was either weaker (P<0.01 relative to SR and SGR without dBSA) or unchanged.