Prostaglandin F(2α) (PGF(2α)) will induce parturition when infused intraaortically into the cranial end of the abdominal aorta of the pregnant rabbit continuously from day 21 of gestation. At a dose of 2.25 μg/h, delivery occurs in 35.8±4.4 hr (mean±S.E.M.; n = 5). When the same dose of PGF(2α) is infused continuously via the inferior vena cava the latency to delivery is much more variable. Out of 6 animals infused intravenously, live litters were delivered in 2 animals 240 and 280 hr after starting the infusion. The remaining 4 rabbits delivered after 39, 69.5, 69.5 and 77.5 hr. The mean and S.E.M. for this group of 4 was 63.9±8.5 hr and that for all 6 intravenously infused animals was 129.25±42.01 hr. When the intravenous groups are compared with those receiving an intraarterial infusion of PGF(2α) the latency to delivery is significantly (P < 0.05) longer in each case. When the PGF(2α) infusion was made intraaortically for a short period (2 to 8 hr) and then stopped, the mean latency to delivery was 93.1±16.7 hr (n = 18). This is significantly (P < 0.01) longer than when the PGF(2α) was infused continuously. This group of 18 animals can be subdivided into those infused for 4 to 8 hr in which delivery occurred in 52.3±3.9 hr (n = 10) and those infused for 2 or 3 hr, in which delivery occurred in 144.1±28.7 hr (n = 8). The difference between these 2 groups is significant (P < 0.01). 2 rabbits infused intraaortically for 1.5 hr with 2.25 μg PGF(2α)/h delivered live litters at term. Preliminary results on 3 animals submitted to different infusion regimes suggest that delivery is accompanied by a fall in plasma progesterone concentrations from 18.9 to 2.6 ng/ml.
|Original language||English (US)|
|Journal||Journal of Endocrinology|
|State||Published - Dec 1 1973|
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism