AJP - Regulatory, Integrative and Comparative Physiology, Vol 248, Issue 1 78-R83, Copyright © 1985 by American Physiological Society
Vasopressin in plasma and ventricular cerebrospinal fluid during dehydration, postural changes, and nausea
P. S. Sorensen and M. Hammer
The responses of plasma and ventricular cerebrospinal fluid (CSF)
vasopressin concentration to dehydration, postural changes, and induction
of nausea were studied in 21 patients with hydrocephalus of various
etiology. The 24-h dehydration test evoked a significant increase in plasma
osmolality and vasopressin concentration, whereas the concentration of
vasopressin in CSF was unchanged. Head-up tilt to 50 degrees for 45 min
with a tilt bed resulted in a modest increase of plasma vasopressin in
patients who did not develop presyncopal symptoms, but no changes were seen
in CSF vasopressin. Induction of nausea by subcutaneously injected
apomorphine provoked a marked (20- to 50-fold) rise in plasma vasopressin
concentration within 15 min, and the plasma concentration was significantly
increased above base-line values for 60-120 min. Despite the prolonged
period of high plasma vasopressin concentration CSF vasopressin was not
influenced by the apomorphine injection. The findings suggest that the
concentration of vasopressin in the CSF is controlled by mechanisms other
than the well-known osmotic and nonosmotic stimuli of vasopressin release
into the blood.
