Calcium deficiency alters chorda tympani nerve responses to oral calcium chloride.

As a preliminary examination of the influence of calcium deficiency on gustatory sensitivity to calcium, we recorded electrophysiological responses of the chorda tympani nerve of calcium-replete and calcium-deprived rats. Relative to rats fed calcium-replete diet, rats fed low calcium diet had lower electrophysiological response thresholds to CaCl2 (300 vs. 30 microM) and calcium lactate (300 vs. 100 microM) but not NaCl. The calcium-deprived animals had a greater chorda tympani response to 30, 100 and 300 microM CaCl2 and 30 and 100 microM calcium lactate but a smaller chorda tympani response to 30, 100 and 300 mM CaCl2 and to 100 mM MgCl2. A behavioral study using an ascending series of 48-h two-bottle preference tests showed that the threshold for acceptance of CaCl2 was similar to the electrophysiological threshold (310 microM in replete rats, 100 microM in calcium-deprived rats). These findings raise the possibility that changes in calcium status influence the perception of calcium, which, in turn, influences calcium intake.