The Clearance of Neurohypophysial Hormones From the Circulation of Non‐mammalian Vertebrates

Abstract

METHODSHens and cockerels (White Leghorns and Rhode Islands obtained commercially), weighing from 1.0 to 2.0 kg, were used. The birds were anaesthetized with pentobarbitone sodium (55 mg/kg) and received heparin 1,000 u./kg. Intravenous injections were given into the brachial vein and the blood samples were collected from a common carotid artery. Bufo marinus of either sex, weighing 150-300 g, obtained from the West Indies were used. Anaesthesia was produced by immersing the toads in a 0.2% solution of MS222 (Sandoz). Intravenous injections were given into the femoral vein and the blood samples were collected from the carotid arch after heparin (1,000 u./kg) had been administered. Adult albino rats of both sexes, weighing from 150 to 200 g were used for assays. Assay of antidiuretic activityThe original technique of Jeffers, Livezey & Austin (1942) was employed with slight modifications. The rats were fasted overnight but were allowed to drink water. On the day of the assay warm tap water 50 ml./kg body weight was given by stomach tube and 45 min later the same volume of 12% ethanol by the same route. If the depth of anaesthesia produced by ethanol was not adequate for surgical operations, 3 mg of pentobarbitone sodium was administered intraperitoneally. As soon as surgical anaesthesia had been obtained a jugular vein was cannulated, as were the stomach and the urinary bladder, and the penile urethra was ligatured. Tracheotomy was also performed to ensure a free airway. The rat was then laid on its back

Inactivation of Oxytocin and Synthetic Oxytocin Analogues by Hen Tissues

“…L-Cystine aminopeptidase activity identified in hen serum could be responsible for this inacti¬ vation (Gilbert & Lake, 1964;Suska-Brzezinska & Ewy, 1965;Suska-Brzezinska, 1971). However, Hasan & Heller (1968) were unable to demonstrate inactivation of oxytocin and vasotocin by hen plasma.…”

Pressor Effects of Neurohypophysial Peptides in the Eel, Anguilla Anguilla L., With Some Reference to Their Interaction With Adrenergic and Cholinergic Receptors

“…In both homeothermic and poikilothermic vertebrates, the biological half-life of neurohypophysial hormones in the blood is of very short duration (see Heller & Ginsburg, 1966 ;Hasan, 1967). Yet in the eel, this peptide caused a prolonged vascular effect lasting about 8 hr.…”