Influence of Strain and Diet on Urinary pH in Laboratory Mice.

Abstract

Simple SummaryDietary cation anion balance (DCAB) influences urine pH in several species, e.g., cats, dogs, pigs and cattle suggesting a species-specific impact. In the present study, we aimed to explore the impact of three diets with different DACB on wildtype laboratory mice. During a two-month feeding trial urine pH and body weight were measured in C57Bl/6J and CD1 male mice. Remarkable, we observed strong impact of the genetic background and diet on urine pH levels. A plausible explanation is that differences in renal phosphorus excretion and, in turn, phosphate buffering capacity account for these differences. It is tempting to speculate that standard laboratory mouse models show DCAB dependent variations in urine pH.Acid base homeostasis and urine pH is influenced by the dietary cation anion balance (DCAB) in many species. Here, a negative DCAB acidifies the urine, while higher DCABs alkalize the urine. The dimension of the DCAB effect can be species-specific, because of differences in urine buffer systems. The aim of the present study was to describe the response of laboratory mice to diets with different DCAB. We used 8-week-old wildtype male mice of the C57Bl/6J inbred strain and CD1 outbred stock. Three groups (n = 15 animals/group) were formed and fed standard diet A for adaptation. For the 7-week feeding trial, mice were either kept on diet A (DCAB −7 mmol/kg dry matter (DM) or switched to diet B (246 mmol/kg DM) or C (−257 mmol/kg DM). Urine pH was measured weekly from a pooled sample per cage. There was a significant difference in the basal urine pH on diet A between C57Bl6/J and CD1 mice. The shift in urine pH was also significantly different between the two groups investigated.