title: Radioimmunoassay of arginine vasopressin in Rhesus monkey plasma.
abstract: Using a new antiserum, an enzymatic radioiodination of arginine vasopressin (AVP), and the methodology of Robertson et al. (1,2), we have developed a sensitive and specific radioimmunoassay for plasma AVP in the monkey. The sensitivity of the assay is 0.5 muU/ml, the cross reaction with oxytocin (OT), minimal. We used this assay to study the effects that variations in blood osmolality have in regulating AVP secretion in unanesthetized, chair-restrained, chamber-isolated, adult female rhesus monkeys. Under water ad lib conditions, plasma AVP and osmolality were relatively constant, averaging 1.7 +/- 0.6 (SD) muU/ml and 298 +/- 3 mosmol/kg, respectively. Water loading decreased plasma AVP and osmolality to 0.6 +/- 0.2 muU/ml and 282 +/- 6 mosmol/kg, respectively. When fluid restriction increased osmolality, plasma AVP rose progressively to twice the baseline after 1 day, and to 6 times the baseline after 3 days. The rise in plasma AVP was linearly correlated with the rise in osmolality (r = 0.93; P less than 0.001). Intravenous infusions of hypertonic saline produced significant rises in plasma osmolality and plasma AVP. There was a dose-related rise in plasma AVP that declined later at the expected rate with the infusion of physiological amounts of synthetic AVP.
mesh_terms: D000818:Animals; D000906:Antibodies; D001127:Arginine Vasopressin / Q000097:blood* / Q000276:immunology; D000882:Haplorhini; D008251:Macaca / Q000097:blood*; D008253:Macaca mulatta / Q000097:blood*; D011863:Radioimmunoassay / Q000379:methods; D014667:Vasopressins / Q000031:analogs & derivatives*
chemical_list: D000906:Antibodies; D014667:Vasopressins; D001127:Arginine Vasopressin