Oxytocin deficiency at delivery with epidural analgesia.

The effect of epidural analgesia on oxytocin release during the second stage of normal labour was studied by comparing 10 primigravidae who had epidurals with 10 control subjects who did not have epidurals. A significant increment in oxytocin between paired peripheral blood samples taken at the onset of full cervical dilatation and crowning of the fetal head was found in the control subjects but not in those with epidurals. Forceps delivery was required more often in the group with epidural analgesia and was associated with lower oxytocin levels at crowning.

The vasotocin-like biological activity present in the bovine pineal is due to a compound different from vasotocin.

The vasotocin-like biological activity detected in an extract (E5 fraction) of bovine pineal gland was found not to be due to the presence of vasotocin, vasopressin or oxytocin. The data obtained by means of bio- and radioimmunoassays suggest that the peptide responsible for this biological activity, however, possess the same Pro-Arg-Gly(NH2) tripeptidic carboxy-terminal end as vasotocin.

Studies on the mechanism of polyuria induced by cortisol excess in the dog.

Water balance studies were performed in 7 experimental dogs before and during a period of cortisol-induced polyuria and in one dog with spontaneous hyperadrenocorticism before and after removal of an adrenocortical carcinoma. Measurements of urine and plasma osmolality and plasma arginine vasopressin concentration were made at regular intervals during the water deprivation studies. The results indicate that cortisol does not block the release of vasopressin but interferes with its action in the kidney.