Contractile effect of PGF2α 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.