Feeing Drinking Interaction Efficacy of Saline Solutions for Ingestion of Dry Food in Rats

Rats were deprived of food and water for 24hr and given food and one of the following liquids: water, .3 per cent, .6 per cent, .9 per cent, 1.8 per cent NaCl solutions, or a condition with no liquid as the baseline level. Food and a liquid (or no-liquid) were presented for 2hr to measure intake. The results show that (a) rats drank more isotonic saline (.9 per cent) than other hypo- or hypertonic saline solutions, (b) rats ate more food with water, and food intake declined as the accompanying solution increased in NaCl concentration, and (c) rats drank more liquid to eat the same amount of food beyond the baseline level as NaCl in liquid increased. NaCl appears to reduce the effectiveness of liquid to reduce thirst which is induced by ingestion of dry food. Increased intake of dilute saline solutions may be partly due to their reduced hydrating capability compared with water.