HORMONAL RESPONSE TO RESTRAINT IN RHESUS-MONKEYS

The purpose of this study was to characterize the hormonal responses t o a restraining system in four adult male rhesus monkeys (Macaca mulat ta) in preparation for a spaceflight project. After the monkeys were a ccustomed to food and water (Phase I), blood-volume-regulating hormone s were measured during three phases: 10 days in a metabolic cage (Phas e II), 16 days sitting in a restrained position in a specially designe d metabolism chair (Phase III) and 10 days in metabolic cage (Phase IV ). An increase of active renin (30%) and vasopressin (25%) was observe d at the end of Phase III. A decrease of atrial natriuretic peptide (A NP), urodilatin, and sodium excretion occurred during the first days o f Phase III. Catecholamines were unchanged. A dramatic increase (tenfo ld) in urinary excretion of growth hormone occurred during all of Phas e III and at the beginning of Phase IV. These findings are similar to those found in man during isolation inactivity and during confinement stress.