AJP - Regulatory, Integrative and Comparative Physiology, Vol 245, Issue 4 549-R555, Copyright © 1983 by American Physiological Society
Vasopressin in blood and third ventricle CSF during dehydration, thirst, and hemorrhage
E. Szczepanska-Sadowska, D. Gray and C. Simon-Oppermann
Samples of cerebrospinal fluid (CSF) were collected from the anterior part
of the third cerebral ventricle of mongrel dogs with a chronically
implanted device. Repeated experiments with simultaneous sampling of CSF
and venous blood in 60- to 90-min intervals were performed in conscious
dogs after 24-h water deprivation and during subsequent rehydration by
drinking, during thirst stimulation by intravenous infusion of 5% saline,
and during blood removal (12 ml X kg body wt-1). The CSF and plasma samples
were analyzed for osmolality and arginine vasopressin (AVP) with a
radioimmunoassay. Compared with normally hydrated dogs, 24-h water
deprivation caused plasma AVP to rise significantly from 2.5 to 7.7 pg X
ml-1 and CSF AVP from 24.2 to 31.3 pg X ml-1. Subsequent drinking
significantly reduced plasma and CSF AVP. Thirst stimulation by hypertonic
infusions was associated with rises of plasma and CSF AVP. Modest reduction
of blood volume also increased both plasma and CSF AVP. Plasma AVP in each
of the described physiological disturbances of salt or fluid balance was
positively correlated with CSF AVP.
