Changes in active and latent collagenase in human placenta around the time of parturition

Article Abstract:

The placenta is an organ that develops during pregnancy to provide nutrition, a means of respiratory gas exchange, hormones, and growth factors to the fetus. The placenta is a rich source of the fiber-like protein collagen, which is found in connective tissues such as skin, bone, ligaments, and cartilage. The placenta also contains enzymes called proteinases that break down structural proteins such as collagen. The enzyme collagenase, which specifically degrades collagen, may be important in dilating the opening of the uterus (cervix) during birth of the baby. The degradation of structural proteins such as collagen may also be important in the separation of the placenta from the wall of the uterus during birth. High levels of collagenase have been measured in fluids from the cervix and in the blood of women at the end of pregnancy. The collagenase content of the human placenta at the end of gestation, the role of circulating collagenase, and the changes that occur at childbirth were assessed. The active and latent forms of the enzyme collagenase were detected in the human placenta. A factor that prevents the action of collagenase was also detected in the placenta. When the collagenase inhibitor was inactivated, collagenase activity increased 12- to 17-fold. The levels of collagenase in the umbilical cord were lower than levels in the circulation of the mother. Collagenase detected in the circulation may originate from the placenta. (Consumer Summary produced by Reliance Medical Information, Inc.)

Analysis, Childbirth, Delivery (Childbirth), Placenta, Parturition, Parturition (Animals), Collagenases

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The angiotensin II antagonist saralasin inhibits ovulation in the perfused rat ovary

Article Abstract:

The angiotensin II antagonist saralasin appears to block ovulation in rat ovaries. Angiotensin is the most potent known stimulator of blood vessel constriction and plays a role in stimulating the heart and nervous system and hormonal production and release. The average number of eggs released per ovary by rats treated with saralasin was 6.6 compared with 18.6 eggs released per ovary in normal rats. When rats were simultaneously treated with saralasin and angiotensin, the average number of eggs released per ovary was 14 in both the treated and untreated rats. When the dose of saralasin was varied, ovulation decreased with increasing dosage. These findings suggest that angiotensin II mediates ovulation.

Prevention, Angiotensins

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Saralasin-induced inhibition of ovulation in the in vitro perfused rat ovary is not replicated by the angiotensin II type-2 receptor antagonist PD123319

Article Abstract:

Angiotensin II inhibits ovulation and lowers prostaglandin E levels but this effect is not mediated via the angiotensin II type 2 receptor. This was the conclusion of a study of the effect of saralasin and the chemical PD123319 on ovulation and prostaglandin E levels in rats. Saralasin blocks the action of angiotensin II and PD123319 blocks activity specifically at the angiotensin II type 2 receptor. Saralasin inhibited ovulation in the rats and decreased prostaglandin E levels. However, PD123319 had no effect on ovulation or prostaglandin E levels.

Angiotensin receptors

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