AJP - Regulatory, Integrative and Comparative Physiology, Vol 232, Issue 3 88-R92, Copyright © 1977 by American Physiological Society
Drinking following intracarotid infusions of hypertonic solutions in dogs
R. J. Wood, B. J. Rolls and D. J. Ramsay
Eight dogs were prepared with bilateral carotid loops and trained to stand
quietly in a modified Pavlov stand. In each of the dogs, 0.3, 0.45, and 0.6
M NaCl were infused, split between the two carotids at a rate of 0.6
ml-kg-1-min-1 for 10 min and the effect on drinking assessed. A graded
increase in drinking was obtained with increased osmolality of the saline
(R = 0.59, N = 32, P less than 0.001). Infusion of 0.3 M NaCl was
associated with an increase in jugular venous osmolality, but no
significant increase in systemic osmolality. Intravenous infusion of 0.3 M
NaCl at 0.6 ml-kg-1-min-1 had no effect on drinking. Intracarotid infusion
of 0.3 M sucrose in 0.15 M NaCl stimulated drinking to a similar extent as
0.3 M NaCl, whereas intracarotid 0.3 M urea in 0.15 M NaCl had no effect.
Increasing the systemic plasma osmolality by infusing 1.04 M NaCl
intravenously stimulated drinking, an effect which was abolished by
removing the central osmotic stimulus with intracarotid infusions of water.
These results are compatible with a central osmoreceptor theory of thirst.
