Liquid intake, initiation and amount of eating as determined by osmolality of drinking liquids

Abstract

In the first part of the study rats were deprived of water for 24 hr and given either water, 0.1 osm, 0.2 osm or 0.3 osm of NaCl, glucose, or sucrose solutions and powdered food. The amount and duration of liquid intake before rats initiated eating were measured. Liquid was removed as soon as eating started and the amount of food intake during 2 hr period was recorded. In the second part of the study 24 hr water-deprived rats were given 8 ml either of water, 0.1 osm or 0.3 osm of NaCl, glucose, or sucrose solutions and then food for 2 hr. The duration of liquid intake and the amount of food intake were measured. The results show that: (a) when there is an increase in osmolality the liquid is drunk more and longer before eating is started; (b) the amount of subsequent food intake is unequal; (c) with the intake of 8 ml liquid the amount of food intake is less the higher the osmolality in drinking liquid; and, (d) with glucose solutions no above mentioned osmotic inhibitive effect on food intake is observed. Beside body fluid osmotic factor there seem to be nonosmotic factors which can contribute to initiation of feeding.