Effects of Saline Infusion on Plasma Levels of Vasotocin(AVT)and Mesotocin in Laying Hens(Gallus domesticus).

Abstract

Plasma levels of immunoreactive arginine vasotocin (AVT) and mesotocin (MT) were measured in conscious, laying hens in response to hypo- and hypertonic saline infusion. Under local anesthesia cannulas were placed in a wing artery for blood collection and measurement of blood pressure and in a wing vein for saline infusion. After obtaining an initial, pre-infusion blood sample, 0.1M NaCl solution was infused i.v. for 30min at 0.5ml/min/kg followed by 1.0M NaCl for an additional 30min (total infusion time: 60mm). Additional blood samples were collected every 10min beginning 20min after starting i.v. infusion. AVT and MT were measured in plasma extracts using radioimmunoassays. Changes in osmolality and plasma AVT and MT concentrations were not observed during 0.1M NaCl infusion. The infusion of 1.0M NaCl caused plasma concentrations of Na and AVT to increase whereas there were significant decreases in hematocrit values and plasma levels of MT. The results suggest that an increase in plasma osmolality or Na may be involved in stimulation of AVT release and inhibition of MT release.