UDI RON A1 and ABRAHAM HAIM A1
A1 Department of Biology, University of HaifaOranim, Qiryat Tivon 36006, Israel
The impact of increasing salinity in drinking water on resting metabolic rates(RMR) and non-shivering thermogenesis (NST) was studied in golden spinymice Acomys russatus. Mice were acclimated to an ambient temperature of27 C under a photoperiod regime of 12L:12D for three weeks. Salinity was increased gradually from 1 to 7% NaCl. Mice were kept for 14 days at each concentration. At the end of each acclimation to a given NaCl concentration, urine was collected and RMR and NST were determined. NST was measured as the maximal response of oxygen consumption (VO2NA) and body temperature (TbNA) to a noradrenaline (NA) injection. Results revealed that under 7% NaCl, urine volume decreased significantly while urine osmolarity increased significantly (p < 0.001 for both variables) compared to mice acclimated to 1% NaCl. Furthermore, body mass and RMR also decreased significantly (p < 0.05 for both variables) in 7%NaCl-acclimated mice compared to mice kept on 1% NaCl. However, NST capacity (the ratio of VO2NA to RMR) significantly increased in such mice. The increased NST-capacity is due to the significant decrease of RMR values rather than a change in VO2NA values. This is in agreement with results from other desert-adapted species, heat-acclimated and heat-adapted rats.
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