Long-term dietary nitrate supplementation does not reduce renal cyst growth in experimental autosomal dominant polycystic kidney disease

• Published in: PloS one Vol. 16; no. 4; p. e0248400
• Main Authors: Zhang, Jennifer Q J, Saravanabavan, Sayanthooran, Cheng, Kai Man, Raghubanshi, Aarya, Chandra, Ashley N, Munt, Alexandra, Rayner, Benjamin, Zhang, Yunjia, Chau, Katrina, Wong, Annette T Y, Rangan, Gopala K
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 22-04-2021; Public Library of Science (PLoS)
• Subjects: Animal models; Arginine; Biology and Life Sciences; Cysts; Data analysis; Deoxyribonucleic acid; Diet; Dietary supplements; DNA; DNA damage; Drinking water; Drug therapy; Ecology and Environmental Sciences; Editing; Epithelial cells; Epithelium; Hospitals; Hypertension; Kidney diseases; Kidney transplantation; Kidneys; Long-term effects; Measurement methods; Medical research; Medicine; Medicine and Health Sciences; Methodology; NG-Nitroarginine methyl ester; Nitric oxide; Nitric-oxide synthase; Physical Sciences; Physiological aspects; Polycystic kidney; Polycystic kidney disease; Renal failure; Research and Analysis Methods; Reviews; Single-nucleotide polymorphism; Sodium nitroprusside; Substrates; Testing; Visualization; Australia; United States > US; New South Wales Australia
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0248400

Augmentation of endogenous nitric oxide (NO) synthesis, either by the classical L-arginine-NO synthase pathway, or the recently discovered entero-salivary nitrate-nitrite-NO system, may slow the progression of autosomal dominant polycystic kidney disease (ADPKD). To test this hypothesis, the expression of NO in human ADPKD cell lines (WT 9-7, WT 9-12), and the effect of L-arginine on an in vitro model of three-dimensional cyst growth using MDCK cells, was examined. In addition, groups of homozygous Pkd1RC/RC mice (a hypomorphic genetic ortholog of ADPKD) received either low, moderate or high dose sodium nitrate (0.1, 1 or 10 mmol/kg/day), or sodium chloride (vehicle; 10 mmol/kg/day), supplemented drinking water from postnatal month 1 to 9 (n = 12 per group). In vitro, intracellular NO, as assessed by DAF-2/DA fluorescence, was reduced by >70% in human ADPKD cell lines, and L-arginine and the NO donor, sodium nitroprusside, both attenuated in vitro cyst growth by up to 18%. In contrast, in Pkd1RC/RC mice, sodium nitrate supplementation increased serum nitrate/nitrite levels by ~25-fold in the high dose group (P<0.001), but kidney enlargement and percentage cyst area was not altered, regardless of dose. In conclusion, L-arginine has mild direct efficacy on reducing renal cyst growth in vitro, whereas long-term sodium nitrate supplementation was ineffective in vivo. These data suggest that the bioconversion of dietary nitrate to NO by the entero-salivary pathway may not be sufficient to influence the progression of renal cyst growth in ADPKD.