Purine modulation of prostaglandin F2 alpha (PGF2 alpha)-induced premature luteolysis in vivo in nonpregnant sheep.

In two separate experiments, control and PGF2 alpha-treated unilaterally ovariectomized ewes received vehicle or adenosine every four hours through an exteriorized catheter installed either to parafuse the ovarian vascular pedicle of the remaining ovary containing a corpus luteum (CL) or to infuse intrauterine ipsilateral to the remaining ovary with the CL. Infusions were given every four hours from day 7 through day 22 postestrus or until ewes returned to estrus. Chronic infusion of vehicle intrauterine or parafusion of the ovarian vascular pedicle with vehicle in PGF2 alpha-treated ewes shortened the interestrous interval compared to controls (P less than 0.05). However, chronic parafusion of the ovarian vascular pedicle with adenosine in PGF2 alpha-treated ewes prevented a PGF2 alpha-induced premature luteolysis (P less than 0.05) but not when adenosine was infused chronically intrauterine (P greater than 0.05). It is concluded that adenosine can block a PGF2 alpha-induced premature luteolysis in vivo and may have roles in regulation of luteal secretion of progesterone but it is probably not the embryonic antiluteolysin of early pregnancy in ewes.