HYPERTONIC INJECTIONS BLOOD CHANGES AND INITIATION OF DRINKING

In Exp. I 24 rats satiated for water were subcutaneously injected with .87, 4, 8, or 16% NaCl. Variability in latency to drink decreased with increases in injection concentration. Mean reciprocal latencies differed between isotonic and hypertonic conditions, but the hypertonic injection means were similar. Water intake in response to injections was a monotonic increasing function of concentration. In Exp. II heart blood samples were taken from 36 Ss at postinjection intervals of 2, 5, 8, or 11 min. Both osmotic pressure and plasma volume increased with time after hypertonic injections. Drinking was initiated by an increase of approximately 1% in plasma osmolality. (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1968 American Psychological Association.