Voluntary sodium chloride consumption by mice: differences among five inbred strains

Abstract

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 48-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 increasing rather than the decreasing series. However, irrespective of the 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/J, and C57BL/6ByJ strains were intermediate between the NZB/B1NJ and the CBA/J strains, but their distributions varied from concentration to concentration. Low (< or = 150 mM) NaCl concentrations were avoided by the C57BL/6ByJ and CBA/J mice, but the NZB/B1NJ, SM/J and 129/J mice either preferred or were indifferent to them. High (> or = 300 mM) NaCl concentrations were strongly avoided by all mice, except for the NZB/B1NJ strain. It is suggested that separate genes underlie the strain differences in acceptance of dilute and concentrated NaCl solutions.

Fig. 1

Fluid intake (upper four rows) and NaCl preference (bottom row) in mice of five strains. NaCl solutions were tested in the ascending (left) or descending (right) order of concentrations. Each concentration was tested in a 48-h test. Intakes were expressed per mouse (top three rows) or per 30 g of body weight (BW; fourth row). Vertical bars represent SE.

Fig. 2

Average daily NaCl and water intakes per mouse (top) and per 30 g BW (middle), and NaCl preference (bottom), by mice of five strains. Vertical bars represent SE. Horizontal lines show homogeneous subsets of means for NaCl intakes or preferences not different (p ≥ .05) in Newman–Keuls post hoc tests.