PLASMA ARGININE VASOTOCIN AND ANGIOTENSIN-II RESPONSES TO BODY-TEMPERATURE ELEVATION IN THE PEKIN DUCK

The relationship between body temperature (T-b) and the plasma concent rations of arginine vasotocin (AVT) and angiotensin II (AII) was exami ned in conscious, adult Pekin ducks. Exposure of birds to an ambient t emperature of 40 degrees C for 3 h increased T-b by about 1.5 degrees C and increased breathing rate five-fold. Plasma osmolality was elevat ed from the normothermic value of 294.9 +/- 1.4 mosmol kg(-1) by about 8 mosmol kg(-1) Circulating AVT levels increased by about 2 pg ml(-1) from a basal concentration of 4.98 +/- 0.15 pg ml(-1), a rise which c ould be accounted for by the change in osmotic status. Plasma AII conc entrations were unchanged from the pre-heat exposure value of 31.8 +/- 3.4 pg ml(-1). Time control birds, exposed only to an ambient tempera ture of 22 degrees C demonstrated no significant changes in any of the measured variables. The results suggest that an increased T-b has no direct effect on the circulating concentrations of AVT or AII in ducks .