• DOI:10.1111/j.2042-7158.1957.tb12292.x
• Corpus ID: 39602495

THE ASSAY OF OXYTOCIN IN THE PRESENCE OF VASOPRESSIN ON THE DIOESTRUS UTERUS OF THE RAT

@article{Lockett1957THEAO,
  title={THE ASSAY OF OXYTOCIN IN THE PRESENCE OF VASOPRESSIN ON THE DIOESTRUS UTERUS OF THE RAT},
  author={Mary F. Lockett and Gwilym Ellis Lane Owen},
  journal={Journal of Pharmacy and Pharmacology},
  year={1957},
  volume={9}
}

• M. Lockett, G. Owen
• Published 1 September 1957
• Biology, Medicine
• Journal of Pharmacy and Pharmacology

EXTRACTS of whole posterior pituitary lobes of cattle are known to contain oxytocin and vasopressin in nearly equal proportions. Since oxytocin is assayed in these extracts, the circumstances under which, and the extent to which, vasopressin may interfere with these estimates should be known. Oxytocin is now assayed either by its depressor action on the fowl's blood pressure1 or by the graded contractions which it induces in the rat's dioestrus uterus2. Whereas the possible interference by vasopressin in the assay of oxytocin by the fowl depressor method has been investigated3, no such study has been made of the rat uterus method. The purpose of this investigation has therefore been to define, if possible, the conditions under which the dioestrus uterus of the rat can be used reliably to assay oxytocin contained in extracts of powders made from whole posterior lobes of the pituitary body. Previous work on the uterus of the virgin guinea pig by Fraser4 and by Stewart5 showed that vasopressin exerted increasing oxytocic action on the uterus of this species as the magnesium content of the Ringer's ,solution was increased. Stewart5 found, over all, that increase in magnesium concentration sensitised the guinea pig uterus more to vasopressin than to oxytocin, and that these uteri were almost equally sensitive to the two hormones at a concentration of 0.1 per cent (w/v) of magnesium chloride. Varying concentrations of calcium were also found to influence the sensitivity of the guinea pig uterus differently to oxytocin and to vasopressin. Concentrations of calcium chloride ranging from 0.029 to .0.034 per cent (w/v) predominantly potentiated the action of oxytocin on the guinea pig uterus, whereas higher concentrations of calcium chloride, ranging from 0.034 to 0.049 per cent (w/v), increased the responses of these uteri more to vasopressin than to oxytocin. This earlier work on the guinea pig uterus has largely directed our study of the effect of variation in the concentration of individual ions on the responses of the dioestrus uterus of the rat to oxytocin and to vasopressin.