VOLUNTARY SODIUM-CHLORIDE CONSUMPTION BY MICE - DIFFERENCES AMONG 5 INBRED STRAINS

We examined voluntary NaCl intakes of five mouse strains: NZB/B1NJ, SM /J, 129/J, C57BL/6ByJ, and CBA/J. Using two-bottle tests with water as one choice, the mice were offered series of progressively increasing or progressively decreasing NaCl concentrations (37.5-600 mM NaCl in 4 8-h tests), then 300 mM NaCl for 6 days and 75 mM NaCl for 8 days. Low concentrations of NaCl were more avidly accepted by mice given the in creasing rather than the decreasing series. However, irrespective of t he test order, test duration, or how the results were expressed (i.e., as raw intakes, intakes corrected for body weights, or preferences), the NZB/B1NJ mice always had higher NaCl acceptance than did the CBA/J mice. The SM/J, 129/5, and C57BL/6ByJ strains were intermediate betwe en the NZB/B1NJ and the CBA/J strains, but their distributions varied from concentration to concentration. Low (less than or equal to 150 nM ) NaCl concentrations were avoided by the C57BL/6ByJ and CBA/J mice, b ut the NZB/B1NJ, SM/J and 129/J mice either preferred or were indiffer ent to them. High (greater than or equal to 300 mM) NaCl concentration s were strongly avoided by all mice, except for the NZB/B1NJ strain. I t is suggested that separate genes underlie the strain differences in acceptance of dilute and concentrated NaCl solutions.