Peripheral angiotensin II stimulates release of vasotocin in conscious chickens

Abstract

In mammals, intracranial or peripheral administration of angiotensin II (ANG II) has a number of actions, including the release of antidiuretic hormone (ADH). Relatively little is known of the interactions between the renin-angiotensin and ADH systems in birds. In the present study [Asp1, Val5]ANG II (fowl ANG II) was infused intravenously into conscious White Leghorn cockerels to determine whether peripheral ANG II influences the release of arginine vasotocin (AVT), the avian ADH. Cannulas were inserted into a wing artery and vein under local anesthesia. ANG II was dissolved in 0.154 M NaCl and administered intravenously at 0, 2, 20, and 200 ng X kg-1 X min-1. In a second series of experiments, ANG II was infused in 0.1 and 1.0 M NaCl (200 ng X kg-1 X min-1) to examine the effect of the peptide on osmotic release of ADH. In the three groups administered ANG II in 0.154 M NaCl, plasma AVT before intravenous infusion averaged between 1.8 +/- 0.46 to 2.6 +/- 0.30 microU/ml. In these birds, infusion of ANG II at 2, 20, and 200 ng X kg-1 X min-1 caused plasma AVT to increase over preinfusion means by 39, 78, and 300%, respectively. The changes in AVT occurred in the absence of differences in plasma osmolality, electrolyte composition, or arterial blood pressure among the groups. In chickens that were administered ANG II in 0.1 and 1.0 M NaCl, significantly higher plasma AVT levels were observed compared with a control group receiving the saline infusions alone.(ABSTRACT TRUNCATED AT 250 WORDS)