A comparative study of renal function in the desert-adapted spiny mouse and the laboratory-adapted C57BL/6 mouse: response to dietary salt load.
The desert-adapted spiny mouse has a significantly lower glomerular number, increased glomerular size, and a more densely packed renal papillae compared with the similar-sized laboratory-adapted C57BL/6 mouse. In the present study we examined the functional consequences of these structural differences in young adult male spiny and C57BL/6 mice and detailed the impact of 1 wk of a high-salt (10% wt/wt NaCl) diet. Basal food and water intake, urine and feces production, and urinary electrolyte concentrations were not different between species, although urinary urea concentrations were higher in spiny mice (P < 0.05). On normal salt, MAP of the anesthetized spiny mouse was approximately 18 mmHg lower, effective renal plasma flow (ERPF) was 40% lower (P < 0.001), and glomerular filtration rate (GFR) tended to be lower than in the C57BL/6 mouse. On the high-salt diet, both species had similar 24-h NaCl excretions; but C57BL/6 mice required a significantly increased amount of water (lower urine NaCl concentration) than the spiny mice. Filtration fraction was greater in both species on the high-salt diet. Spiny mice had greater GFR and ERPF after the high-salt diet, whereas the C57BL/6 mouse showed little change in GFR. The ability of the spiny mouse to tolerate a significantly higher plasma osmolality after salt, measured by a decreased drinking response, and the ability to increase ERPF at a lower MAP are features that allow this species to conserve water more efficiently than can be done in the C57BL/6 mouse. These features are important, particularly since the desert mouse has a smaller kidney, with fewer nephrons.
Dickinson
Hayley
H
Department of Physiology, Monash University, Clayton, Victoria, Australia. hayley.dickinson@med.monash.edu.au
Moritz
Karen
K
Wintour
E Marelyn
EM
Walker
David W
DW
Kett
Michelle M
MM
D000222:Adaptation, Physiological; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002712:Chlorides / Q000652:urine; D004326:Drinking / Q000187:drug effects / Q000502:physiology; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL / Q000502:physiology*; D051189:Murinae / Q000502:physiology*; D009399:Nephrons / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D012964:Sodium / Q000652:urine; D017673:Sodium Chloride, Dietary / Q000378:metabolism / Q000494:pharmacology*
D002712:Chlorides; D017673:Sodium Chloride, Dietary; D012964:Sodium