AJP - Regulatory, Integrative and Comparative Physiology, Vol 267, Issue 2 470-R475, Copyright © 1994 by American Physiological Society
Voluntary intake of calcium and other minerals by rats
M. G. Tordoff
Monell Chemical Senses Center, Philadelphia, Pennsylvania 19108-3308.
The voluntary intake by male Sprague-Dawley rats of five calcium salts and
eight mineral chlorides was assessed. Groups of 12-25 rats received a
series of 48-h two-bottle tests with a choice between water and ascending
concentrations of a mineral solution. Similar inverted U-shaped
concentration-intake functions were obtained with each of the five calcium
salts tested (hydroxide, gluconate, phosphate, lactate, and chloride): rats
drank more calcium solution than water at concentrations between
approximately 0.2 and 5 mM, showed indifference between 5 and 12 mM, and
avoided higher concentrations. Inverted U-shaped concentration-intake
functions were also obtained for ammonium chloride (peak at 100 mM),
magnesium chloride (peak at 10 microM), potassium chloride (peak at 10 mM),
ferrous chloride (peak at 4.64 microM), and rubidium chloride (peak at 2.15
mM). Rats drank slightly and nonsignificantly more 2.15 microM aluminum
chloride than water and never drank more zinc chloride than water (range
tested, 1 microM to 464 mM). These results illustrate that, as is the case
for sodium, rats spontaneously ingest low concentrations of calcium and
several other mineral solutions in preference to water. In general, the
lower the cation's ionic charge, the greater the intake and higher the most
accepted concentration.
