Osmoregulation and water balance in the springhare (Pedetes capensis)
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- Peinke, D. & Brown, C. J Comp Physiol B (1999) 169: 1. doi:10.1007/s003600050187
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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 arid 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.