title: Osmoregulation and water balance in the springhare (Pedetes capensis).
abstract: Springhares are large rodents that live in arid and semi-arid regions of Africa. We deprived springhares of water for periods of up to 7 days to determine what physiological adaptations. If any, enable them to survive in and regions without drinking. During water deprivation, springhares lost up to 30% body weight and produced a mean maximum urine concentration of 2548 mosmol kg-1 with a maximum of 3076 mosmol kg-1 in an individual animal. Haematocrit and plasma sodium and potassium concentrations were well regulated throughout water deprivation at 47.5 +/- 3.8% and 132.6 +/- 7.4 mmol l-1 and 3.5 +/- 0.7 mmol l-1, respectively, while plasma osmolality increased slightly from 293 +/- 12.5 mosmol kg-1 to 324 +/- 7.3 mosmol kg-1. Springhares thus appeared to be good osmoregulators and were able to maintain plasma volume during 7 days of water deprivation. In addition to the production of a relatively concentrated urine, water loss was limited by the lowered solute load and faecal water loss achieved by a reduction in food consumption and by the production of very dry faeces. These abilities, together with a favourable burrow microclimate and nocturnal activity pattern, enable them to survive in arid regions.
authors: Department of Zoology and Entomology, Rhodes University, Grahamstown, South Africa. g90p4513@giraffe.ru.ac.za
authors: D M
authors: DM
authors: Peinke
authors: C R
authors: CR
authors: Brown
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001810:Blood Volume / Q000502:physiology; D006400:Hematocrit; D007668:Kidney / Q000033:anatomy & histology / Q000502:physiology; D007671:Kidney Concentrating Ability / Q000502:physiology; D011188:Potassium / Q000097:blood / Q000652:urine; D012377:Rodentia / Q000097:blood / Q000502:physiology* / Q000652:urine; D012964:Sodium / Q000097:blood / Q000652:urine; D014508:Urea / Q000097:blood / Q000652:urine; D014868:Water Deprivation / Q000502:physiology; D014882:Water-Electrolyte Balance / Q000502:physiology*
chemical_list: D014508:Urea; D012964:Sodium; D011188:Potassium