A comparison of plasma vasopressin and oxytocin concentrations during the oestrous cycle of the ewe D. C.

Wathes, V. J. Ayad, M. Kumari, E. L. Matthews and C. M. Wathes

Department of Anatomy, School of Medical Sciences, University of Bristol, Bristol bss itd, U.K. *AFRC Silsoe Research Institute, Wrest Park, Silsoe, Bedford mk45 4hs, U.K. (D. C. Wathes to whom requests for offprints should be addressed is now at AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge cb2 4at, U.K.) (M. Kumari is now at Department of Pharmacology, Charing Cross and Westminster Medical School, St Dunstan's Road, London w6 8rf, U.K.) received

27 November 1991

ABSTRACT

Blood samples were collected twice daily (09.30 and 17.00 h) via indwelling jugular-vein cannulae from five ewes throughout an entire oestrous cycle. Additional frequent samples were taken at 30-min intervals for 8 h on each of days 3 (early luteal phase), 9 (mid\x=req-\ luteal phase), 12 (late luteal phase) and 0 (day of oestrus). Plasma concentrations of arginine vasopressin and oxytocin were measured in all samples by radioimmunoassay and progesterone was measured in the twice-daily samples only. Both oxytocin and progesterone showed the expected pattern of plasma concentrations, increasing during the early luteal phase, reaching a plateau and declining either preceding (oxytocin) or at (progesterone) luteolysis. Vasopressin concentrations showed a significant dependence on the day of cycle (P

A comparison of plasma vasopressin and oxytocin concentrations during the oestrous cycle of the ewe.

Blood samples were collected twice daily (09.30 and 17.00 h) via indwelling jugular-vein cannulae from five ewes throughout an entire oestrous cycle. ...
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