Contractile effect of PGF2alpha and PGE2 on isolated branches of uterine and ovarian artery in different days of estrous cycle and early pregnancy in pigs

The contractile effects of PGF₂α (3 × 10⁻⁶ to 10⁻⁴ M) and PGE₂ (10⁻⁷ to 10⁻⁵ M) were examined on isolated branches of ovarian artery (OA) and extramyometrial branches of uterine artery (UA) collected from pigs in the luteal (day 10-12) and follicular phase (day 17-20) of the estrous cycle, and during early pregnancy (day 10-12). Strong contraction was demonstrated in both arteries during all investigated periods in response to PGF2α, which was significantly higher (P < 0.01) than to PGE₂, being negligible in the follicular phase. In UA, the effective dose of PGF₂α (ED50) amounted 7.9 × 10⁻⁶ M and 6.3 × 10⁻⁶ M in the luteal and follicular phase, and 5.0 × 10⁻⁶ M in early pregnancy. ED50 for PGE₂ reached 5.0 × 10⁻⁷ M in the luteal phase, and 4.1 × 10⁻⁷ M in early pregnancy. For both prostaglandins, the contraction was much stronger (P < 0.01) in OA than in UA branches. In OA, the ED50 for PGF₂α was 1.2 × 10⁻⁵ M in the luteal phase and was significantly higher (P < 0.05) than in the follicular phase (3.1 × 10⁻⁶ M) and early pregnancy (2.7 × 10⁻⁶ M). ED50 for PGE2 amounted 7.3 × 10⁻⁷ M in the luteal phase and 1.7 × 10⁻⁷ M in early pregnancy. Studies showed the influence of the estrous cycle and early pregnancy on OA branches sensitivity to the contractile effect of PGF₂α and the lack of this effect on UA branches, and the influence of the estrous cycle on UA and OA branch contraction in response to PGE2.