Analysis of water and NaCl solution acceptance by schedule-induced polydipsia.

Animals were trained on a VI 1-min schedule for food pellets, and concurrent water intake was measured. The polydipsia induced was analyzed in terms of the frequency distribution of post-pellet licking burst sizes and the trend of polydipsia throughout the session. An ascending series of NaCl solutions was presented consecutively over daily sessions and a typical NaCl acceptance-rejection intake function was generated. Beginning in the 0.9-1.2% NaCl range, the animals drank less often during the session but took larger drinks when they did drink. Neither the frequency of drinks nor the mean licking burst size were simply related to the volumes of NaCl solution consumed. The NaCl acceptance-rejection function cannot be explained in terms of water repletion factors alone.