Chronic metabolic acidosis reduces urinary oxalate excretion and promotes intestinal oxalate secretion in the rat.

Abstract

Urinary oxalate excretion is reduced in rats during a chronic metabolic acidosis, but how this is achieved is not clear. In this report, we re-examine our prior work on the effects of a metabolic acidosis on urinary oxalate handling [Green et al., Am J Physiol Ren Physiol 289(3):F536-F543, 2005], offering a more detailed analysis and interpretation of the data, together with new, previously unpublished observations revealing a marked impact on intestinal oxalate transport. Sprague-Dawley rats were provided with 0.28 M ammonium chloride in their drinking water for either 4 or 14 days followed by 24 h urine collections, blood-gas and serum ion analysis, and measurements of (14)C-oxalate fluxes across isolated segments of the distal colon. Urinary oxalate excretion was significantly reduced by 75% after just 4 days compared to control rats, and this was similarly sustained at 14 days. Oxalate:creatinine clearance ratios indicated enhanced net re-absorption of oxalate by the kidney during a metabolic acidosis, but this was not associated with any substantive changes to serum oxalate levels. In the distal colon, oxalate transport was dramatically altered from net absorption in controls (6.20 ± 0.63 pmol cm(-2) h(-1)), to net secretion in rats with a metabolic acidosis (-5.19 ± 1.18 and -2.07 ± 1.05 pmol cm(-2) h(-1) at 4 and 14 days, respectively). Although we cannot rule out modifications to bi-directional oxalate movements along the proximal tubule, these findings support a gut-kidney axis in the management of oxalate homeostasis, where this shift in renal handling during a metabolic acidosis is associated with compensatory adaptations by the intestine.

• Authors: Jonathan M Whittamore, Marguerite Hatch
• Journal: Urolithiasis (Urolithiasis) Vol. 43 Issue 6 Pg. 489-99 (Nov 2015) ISSN: 2194-7236 [Electronic] Germany
• PMID: 26162424 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Chlorides
• Oxalates
• Creatinine
• Calcium

Topics

• Acidosis (blood, urine)
• Animals
• Calcium (blood)
• Chlorides (metabolism)
• Colon (metabolism)
• Creatinine (urine)
• Male
• Oxalates (blood, urine)
• Random Allocation
• Rats, Sprague-Dawley