Involvement of adrenoceptors in the ovarian vascular pedicle in the regulation of counter current transfer of steroid hormones to the arterial blood supplying the oviduct and uterus of pigs

Abstract

1. On Day 10 of the oestrous cycle in pigs, after laparotomy noradrenaline (NA), methoxamine (α₁-adrenomimetic, M), Prazosin (α₁-adrenolytic, Pr) in total doses of 4 μmol, and saline were infused (10 min) into the superficial layer of mesovarium on both sides of the ovarian pedicle vasculature, close to the ovary.

2. Blood flow in the ovarian artery, heart rate and progesterone (P₄) and androstenedione (A₄) secretion from the ovary and their concentrations in the ovarian venous effluent, as well as the concentrations of P₄ and A₄ in the blood supplying the oviduct and the uterus, were determined.

3. A significant increase of P₄ and A₄ secretion after NA and M infusion and increased concentrations of P₄ and A₄ in the ovarian venous effluent were found, but these changes did not influence the counter current transfer of hormones from the venous effluent into arterial blood supplying the oviduct and the uterus.

4. Infusion of Pr caused a significant decrease of P₄ and A₄ secretion and their concentrations in the ovarian venous effluent and significantly increased A₄ concentration in the blood supplying the oviduct and uterus.

5. The results indicate that stimulation of α₁-adrenoceptors in the area of ovarian vasculature did not influence, whereas block of α₁-adrenoceptors affected, the local concentration of steroid hormones in the blood supplying the oviduct and the part of the uterus proximal to the ovary, despite the changes in the concentrations of steroid hormones in the ovarian effluent.

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