Osmotic stimuli and NaCl-intake in the fowl; release of arginine vasotocin and prolactin.
White Plymouth Rock hens were fed a high- and a low-NaCl content of the diet. The two groups were exposed to moderate dehydration, to intra-arterial hyperosmotic NaCl-loading, or to injection of physiological doses of arginine vasotocin (AVT). The plasma levels of AVT and prolactin were measured by accurate and sensitive radioimmunoassay and the osmolality and Na, K (and Cl) concentrations also measured for 48 h after dehydration, and for 60-90 min after NaCl-loading or AVT-injection. The plasma concentration of AVT after a given increase of plasma osmolality was in all experiments found higher in the low- as compared to the high-NaCl diet group. The average difference was 0.2 pg/ml X mOsm. The intra-arterial injection of AVT resulted in a strictly mono-exponential fall over the next hour with an average half-life of 6.3 min without any difference between the high- and the low-NaCl diet groups. It is concluded (a) that the release of prolactin after osmotic stimulation is most likely caused by a direct effect of osmolality (or Na concentration) and not by AVT, (b) that the release of AVT is influenced by the NaCl-intake in a direction which tends to maintain extracellular volume.
D000818:Animals; D001769:Blood; D002645:Chickens / Q000502:physiology*; D002712:Chlorides / Q000097:blood; D004032:Diet; D005260:Female; D006207:Half-Life; D007700:Kinetics; D009994:Osmolar Concentration; D011188:Potassium / Q000097:blood; D011388:Prolactin / Q000097:blood*; D012462:Saline Solution, Hypertonic; D012964:Sodium / Q000097:blood; D012965:Sodium Chloride / Q000008:administration & dosage*; D014668:Vasotocin / Q000097:blood* / Q000494:pharmacology; D014868:Water Deprivation / Q000502:physiology
D002712:Chlorides; D012462:Saline Solution, Hypertonic; D012965:Sodium Chloride; D011388:Prolactin; D012964:Sodium; D011188:Potassium; D014668:Vasotocin