AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 6 1022-R1028, Copyright © 1984 by American Physiological Society
Salt gland and kidney responses to intracerebral osmotic stimulation in salt- and water-loaded ducks
R. Gerstberger, E. Simon and D. A. Gray
Saltwater-adapted ducks with functioning supraorbital salt glands were
chronically implanted with a device for perfusion of the third cerebral
ventricle (icv perfusion) with artificial cerebrospinal fluid (CSF) of
different tonicities. The osmoregulatory responses to icv stimulation were
studied at conditions of salt and water loading in which only the salt
glands, both salt glands and urinary fluid excretion, or only urinary fluid
excretion were stimulated; in the latter experiments plasma antidiuretic
hormone (ADH) was measured with a radioimmunoassay. Hypertonic icv
stimulation enhanced salt gland secretion and caused antidiuresis, due to
the increase of plasma ADH. Hypotonic icv stimulation inhibited salt gland
activity and caused diuresis, due to the decrease of plasma ADH. Salt gland
activity, urine formation, and plasma ADH reacted more sensitively to
changes of icv tonicity in the hypertonic than in the hypotonic range. The
effect of icv hypotonic stimulation could be obtained also with icv
perfusion of isosmotic artificial CSF deficient in NaCl content. Perfusion
with artificial CSF exceeding plasma tonicity by 50 mosmol X kg-1 or more
caused inhibition of salt gland secretion associated with enhanced urinary
output in several experiments.
