title: Renal physiology of two southern African Mastomys species (Rodentia: Muridae): a salt-loading experiment to assess concentrating ability.
abstract: Aspects of renal physiology were examined to test the hypothesis that two cryptic species of the genus Mastomys (Mastomys natalensis and Mastomys coucha) are geographically separated by differences in aridity tolerance. Laboratory-bred females of each species were subjected to different levels of salinity in their water source (distilled water, 0.9% NaCl, and 1.5% NaCl; 10 conspecifics in each group) from weaning until sexual maturity. Individuals of the two species exhibited similar rates of water consumption and urine production. The salinity treatments caused sodium diuresis in both species, evident in increased urine volume, decreased osmolality and increased osmotic output. Urine concentration, kidney mass and kidney relative medullary area (RMA) did not differ between species. The results of our study do not support the hypothesis that differences in osmoregulatory ability separate these two cryptic species. Nor do they support the use of salt loading to elicit maximum urine concentrations in mammals.
authors.affiliation: Conservation Ecology Research Unit, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa.
authors.forename: Phumza
authors.initials: P
authors.lastname: Ntshotsho
authors.forename: Rudi J
authors.initials: RJ
authors.lastname: van Aarde
authors.forename: Sue W
authors.initials: SW
authors.lastname: Nicolson
authors.forename: Tim P
authors.initials: TP
authors.lastname: Jackson
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004327:Drinking Behavior / Q000187:drug effects; D005260:Female; D007668:Kidney / Q000187:drug effects* / Q000502:physiology*; D007671:Kidney Concentrating Ability / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009115:Muridae / Q000145:classification / Q000502:physiology* / Q000652:urine*; D009929:Organ Size / Q000187:drug effects; D012965:Sodium Chloride / Q000494:pharmacology*; D014867:Water / Q000378:metabolism
chemical_list: D014867:Water; D012965:Sodium Chloride