Macronutrient Combinations Enhance Mitochondrial Function in Precision‑Cut Kidney Slices

In an ex vivo study using precision-cut kidney slices, investigators reported that, in porcine tissue, some nutrient combinations increased ATP versus incubation without nutrients (e.g., glucose plus glutamine or fatty acids plus glutamine).

Mitochondrial oxygen flux measures were also reported as higher with nutrients versus no nutrients after prolonged, normothermic, oxygenated incubation. Experiments were performed in both porcine and human cortical kidney slices, with the incubation medium’s nutrient composition as the primary experimental variable. Across the reported outcomes, the clearest group differences were described after extended incubation in porcine slices rather than in the smaller human series.

The design used porcine kidneys (n=8) and human kidney tissue (n=5) to generate cortical slices incubated under controlled, normothermic, oxygenated conditions with glucose, glutamine, fatty acids, or combinations of these substrates. Porcine slices were followed through 48 hours, while human slices were incubated up to 24 hours, with sampling at 0, 24, and 48 hours where applicable. Incubations were performed at 37°C with an 80% O2/5% CO2 gas phase and gentle shaking (90 rpm) in a base medium of DMEM without glucose, glutamine, or phenol red, supplemented with ciprofloxacin and amphotericin B; nutrients were added to reported end concentrations (D-glucose 11 mmol/L, SMOF lipids 1.5 mg/mL, L-glutamine 2 mmol/L). Tissue energetic status was tracked over time using ATP content and mitochondrial respiration measures.

At 48 hours in porcine slices, ATP content was reported as significantly higher for two combination conditions compared with incubation without nutrients: glucose plus glutamine (p=0.001) and fatty acids plus glutamine (p=0.003). The authors also described ATP levels rising during incubation across groups, while the statistical separation highlighted in the report focused on these combination-versus-no-nutrient comparisons at the prolonged timepoint. In this porcine dataset, ATP preservation was reported primarily with macronutrient combinations rather than with nutrient omission.

Mitochondrial oxygen flux measurements in porcine slices at 48 hours were also reported as higher when all nutrients were provided compared with no nutrients, including ADP-stimulated basal respiration (p=0.040), proton leak (p=0.001), and maximal respiration (p=0.039). The study described these oxygen-consumption parameters as readouts derived from high-resolution respirometry after permeabilization and sequential substrate/inhibitor additions, with oxygen flux expressed as O₂ flux in pmol. In the reported pattern for porcine tissue, broader macronutrient provision aligned with higher respiration readouts at the prolonged incubation endpoint.

For reserve capacity, the authors reported that porcine spare respiratory capacity at 48 hours was significantly higher with all nutrients versus no nutrients (p=0.014) and with glucose plus glutamine versus no nutrients (p=0.039). When porcine slices were incubated with single macronutrients alone (glucose, fatty acids, or glutamine), the report described no significant differences versus no nutrients across the same classes of energetic and respiration outcomes. In human slices, no significant differences in oxygen fluxes or reserve capacity were reported between nutrient groups; the authors noted fewer samples and a shorter incubation than in the porcine work, leaving the porcine results as the most clearly differentiated signal within this dataset.

Key Takeaways:

• The study used porcine and human precision-cut kidney slices incubated under normothermic, oxygenated conditions with measurements at 0, 24, and (for porcine) 48 hours.
• In porcine slices after prolonged incubation, combinations of macronutrients were reported in association with higher ATP content and multiple respiration parameters compared with incubation without nutrients, while single nutrients alone were not reported to differ significantly from no nutrients.
• Human slice experiments did not show differences in mitochondrial oxygen fluxes across nutrient conditions; the authors noted the human data were underpowered and that only trends could be described.