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Abstract: PO0496

Niacin Supplementation Increases In Vitro Apicobasal Volume Transport and Oxygen Consumption by Proximal Tubule Cells

Session Information

Category: Bioengineering

  • 300 Bioengineering

Authors

  • Hunter, Kuniko, Vanderbilt University, Nashville, Tennessee, United States
  • Evans, Rachel C., Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Love, Harold D., Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Parikh, Samir M., The University of Texas Southwestern Medical Center, Dallas, Texas, United States
  • Humes, H. David, University of Michigan, Ann Arbor, Michigan, United States
  • Roy, Shuvo, University of California San Francisco, San Francisco, California, United States
  • Fissell, William Henry, Vanderbilt University Medical Center, Nashville, Tennessee, United States

Group or Team Name

  • The Kidney Project
Background

Renal tubule cells are energetically demanding as they consume ATP to transport salt and water within the kidney. In vitro, renal tubule cells have an attenuated glycolytic phenotype described as cell culture stress. We hypothesized that Krebs cycle intermediates might be rate-limiting for ATP-dependent transport. We tested the influence of supplemental niacin as a source for NAD+/NADH on mitochondrial oxygen consumption.

Methods

Primary human renal tubule epithelial cells (HREC) were seeded on polystyrene tissue culture plates and cultured with normal (2 mg/L) or high niacin (4mg/L). After two weeks of treatment, cell oxygen consumption (OCR) and extracellular acidification rates (ECAR) were assessed using a Seahorse XFe96 analyzer. Respiratory inhibitors oligomycin (2µM), CCCP (2µM), rotenone (0.5µM), antimycin A (0.5µM) and 2-deoxyglucose (2-DG, 50mM), and glucose (10mM) were used to probe mitochondrial and non-mitochondrial respiration. Statistical differences between control and experimental groups were estimated by two-tailed Student’s t-test. Results are considered significant at p<0.05. Cells from the same lot were seeded on permeable supports and cultured with an inhibitor of TGF-b receptor 1 and low or high niacin concentrations. Apicobasal volume transport was measured gravimetrically.

Results

High-dose niacin was associated with increased oxygen consumption compared with normal dose niacin (225 vs 157 uMol/min, p < 0.01), and with increased transport (187 +/- 83 vs 87 +/- 2.8 uL/cm2/day; p < 0.0004).

Conclusion

Our observation that mitochondrial oxygen consumption increased with addition of supplemental niacin supports the hypothesis that Krebs cycle intermediates may be rate-limiting in tubuel cell function. The significant increase in apicobasal transport with added niacin suggest that some of the dysfunctional phenotype induced by cell culture stress may be mitigated by nutritional supplementation.

Funding

  • Private Foundation Support