AJP - Endocrinology and Metabolism, Vol 248, Issue 2 155-E161, Copyright © 1985 by American Physiological Society
Function of vasopressinergic neurons in rats under conscious and anesthetized conditions
S. W. Cheng and W. G. North
The responses of vasopressinergic neurons to acute salt loading and to
graded hemorrhage were studied in rats under conscious and anesthetized
conditions. Chronically cannulated rats were used in this study so that
pre- and postanesthetic conditions could be studied in the same animals.
Anesthesia induced by a combination of ketamine hydrochloride and
pentobarbital sodium (Nembutal) did not cause a release of
vasopressin-associated neurophysin (VP-RNP). In response to infusion of 18%
saline, animals in the anesthetized state had significantly greater
increases in plasma osmolality (Posmol) and plasma sodium concentration
than animals in the conscious state. However, the rate of increase in
plasma VP-RNP concentration ([VP-RNP]) as well as the relationship between
[VP-RNP] and Posmol were not significantly different for the two states.
Graded hemorrhage caused similar rates of increase in [VP-RNP] for animals
under conscious and anesthetized conditions. These data suggest that
anesthesia induced by ketamine plus pentobarbital sodium does not change
the responsiveness of vasopressinergic neurons to acute salt loading and to
graded hemorrhage.
