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Biomedical subjects

M J Harper

Publications and source records attributed to M J Harper.

At least 109 records · Page 6Linked to original sources
PubMed1977

Effect of ovulation and hormonal treatment on the in vitro response of rabbit oviducts to prostaglandins E1 and F2alpha.

Rabbit oviductal circular muscle isometric contractile response was measured in relation to treatment with prostaglandin E1 (PGE1) and prostaglandin F2alpha (PGF2alpha). PGE1 (1 mug/ml) inhibition of the contractile response of the rabbit oviduct to field stimulation was increased in the proximal isthmus after ovulation. Estrogen and progesteron, in doses known to alter ovum transport, did not affect the response of the oviduct to PGE1. In comparison to the response of estrous tissues, the stimulatory effect of PGF2alpha on the isthmus was decreased 24 hours after administration of human chorionic gonadotropin (HCG). Treatment with estrogen and progesterone did not affect these postovulatory changes. The response of the ampullary-isthmic junction to PGF2alpha was significantly reduced 72 hours after administration of HCG. Neither ovulation nor steroid treatment affected the response of the ampulla to PGF2alpha. Changes in the sensitivity of the oviduct to prostaglandins after ovulation may be necessary for successful ovum transport.

Animals↗
PubMed1976

Effect of estrogen on activity of prostaglandin synthetase in rabbit oviduct.

The activity of the prostaglandin synthetase system in the ampulla and isthmus of the rabbit oviduct has been studied in vitro. Thirty hours after an injection of estrogen the isthmus produced significantly more total prostaglandins following 9 minutes of incubation than the ampulla. These values were not, however, significantly different from those observed following 9 minutes of incubation in the same portions of the oviducts of estrous or castrate animals. Furthermore, the total yields of prostaglandins at thirty minutes did not differ significantly between treatment groups.

Animals↗
PubMed1975

Effects of prostaglandins on oviductal motility and egg transport.

The effects of prostaglandins (PGs) on muscular activity of the oviductal isthmus and on the rate of tubal egg transport are reviewed. In consideration of the available data a mechanism by which PGs contribute to the physiological control of egg transport is suggested. In vivo experiments have demonstrated that E-series PGs relax while F-series PGs stimulate muscular activity of the oviduct in humans, subhuman primates and rabbits. These effects are mutually antagonistic. The response of oviductal muscle to PGs appears to be affected by ovarian steroids; progesterone increases the response to PGE1 and decrease the response to PGF2alpha. Oviductal tissue concentrations of PGF increase in a distal to proximal sequence following ovulation-induction in the rabbit. Also, proximal isthmus binding of PGE1 t tended to be greater in 72-hour pregnant rabbits than in estrous rabbits, while binding of PGF2alpha was greater in estrous than in 72-hour pregnant animals. It is suggested that the preovulatory increase in ovarian estradiol secretion stimulates PGF synthesis in the oviductal tissue in a sequential fashion, the peak value occurring when the oviductal isthmus is most sensitive to stimulation by PGF2alpha. The changes in tissue concentration of PGF and in sensitivity to PGF2alpha could contribute to occlusion of the isthmus and prevent premature passage of eggs into the uterus. An increase in ovarian progesterone secretion after ovulation may decrease tissue PGF, decrease the response to PGF2alpha stimulation, and increase the response to PGF1. These changes may then allow a progressive movement of eggs through the isthmus into the uterus. Several questions regarding this proposed mechanism remain unanswered.

Animals↗