Urinary Aldosterone and Urine Volume Responses to 72-Hr. Avoidance Sessions in the Monkey

Abstract

Urinary aldosterone levels showed marked fluctuations in relation to 72-hr. conditioned avoidance sessions in the monkey. Two different response patterns were observed. The first was a biphasic response characterized by an initial depression during avoidance, followed by a rebound elevation during the recovery period. The second was characterized by an elevation, in some cases quite marked, during avoidance with a return to basal level during the recovery period. The principal preavoidance difference noted between the two response subgroups was the occurrence of a substantial mean urinary aldosterone response 1 day before avoidance was started in the group which showed an aldosterone elevation during avoidance. The basis for this preavoidance change is not known, but its possible relation to electrolyte and fluid balance is discussed. An antidiuretic response was most commonly observed in relation to avoidance sessions, although a diuretic response occurred occasionally. The antidiuretic response occurred even when fluid intake was maintained at a constant level. An apparent multiple correlation between excretion of aldosterone, estrogens, and water on the first avoidance day suggests perhaps a common, underlying mechanism or, at least, a close interdependence of these variables, possibly in relation to fluid and electrolyte regulation. This question is in need of further, systematic study.