Laura T. Goldsmith

Myometrial inhibiting activity of relaxin-containing extracts of human corpora lutea of pregnancy

Relaxin is a peptide hormone secreted by the human corpus luteum of pregnancy . Aqueous extracts of relaxin-rich pregnancy corpora lutea decreased the amplitude of spontaneous human myometrial strip contractions in vitro. Relaxin-poor extracts of menstrual cycle corpora lutea did not affect contractions. Antibody precipitation of relaxin from pregnancy luteal extracts eliminated the effect on myometrial strips. Relaxin removal was confirmed by bioassay. This demonstrates an inhibiting action of human relaxin on human myometrial tissue in vitro. This action suggests a mechanism for maintaining uterine quiesence in early pregnancy.

Partial purification of relaxin from human seminal plasma

Human seminal plasma contains approximately 50 ng/ml of relaxin (specific activity = 1.3 ng/mg protein). During preliminary purification, semen plasma was delipidated, rehydrated, and loaded onto small octadecyl silica columns that were eluted with a TEAF/acetonitrile gradient system. Results were monitored by radioimmunoassay. The resultant partially purified human relaxin demonstrated biologic activity in the rat uterine segment bioassay. Nine liters of semen plasma was delipidated, rehydrated in TEAF, and subjected to high-performance liquid chromatography by a step gradient followed by a linear gradient. The active eluate was further purified by ion exchange chromatography. Pooled recovery fractions provided a total of 45.8 micrograms of relaxin. An aliquot flash evaporated and desalted by gel filtration chromatography provided 1.85 micrograms of relaxin in 25.2 mg protein, specific activity 73.4. This material is being used as immunogen in the production of antihuman relaxin antibodies by monoclonal technique. Our procedure represents the first and only successful partial purification of human relaxin to yield sufficient quantity and purity for antibody production.

SYNERGISTIC EFFECT OF HUMAN RELAXIN AND PROGESTERONE ON HUMAN MYOMETRIAL CONTRACTIONS

In an in vitro human myometrial strip system, both relaxin and progesterone can independently decrease the amplitude of spontaneous myometrial contractions. However, progesterone and relaxin synergize in this action. Doses of relaxin and progesterone which independently are ineffective, together inhibit myometrial contraction amplitude. Relaxin and progesterone are both products of the corpus luteum, a structure necessary for early pregnancy maintenance. The synergistic action of relaxin and progesterone in vitro suggests a similar in vivo physiologic effect in establishing uterine quiescence.

IN VITRO INDUCTION OF RELAXIN SECRETION IN CORPORA LUTEA FROM NONPREGNANT RATS

In the rat, relaxin is detected by bioassay and/or immunoassay in the ovaries and blood only during the second half of Results of studies by Sherwood et ~ 1 . ~ show that the ovary is the source of circulating relaxin during rat pregnancy. No relaxin immunoactivity nor biological activity was found in extracts of rat uteri or placentae obtained from late pregnant rats, in contrast to high levels of immunoactivity and biological activity in ovarian extracts from these animals. Furthermore, results of studies by Anderson et aL4* provide evidence that the corpus luteum, rather than other regions of the ovary, is the source of relaxin in pregnant rats. It has yet to be determined, however, which factors control the secretion of relaxin from the rat corpus luteum. The present studies describe the establishment of a rat luteal cell monolayer culture system and the use of this system in evaluation of certain luteotropic factors in the control of relaxin secretion.

Effect of Human Placental Lactogen upon the Human Corpus luteum of Late Pregnancy

To acertain whether human placental lactogen (HPL) functions as a luteotropin during pregnancy in humans, studies were performed to determine if receptors for HPL are present in cells of the human corpus luteum of late pregnancy. Preparations of 125I-HPL which demonstrated specific binding to late pregnant rabbit mammary gland cell homogenates showed specific binding of less than 2.5% to homogenates of human corpora lutea of late pregnancy. These studies indicate that HPL is not luteotropic at this stage of pregnancy in humans. The action of HPL upon the corpus luteum appears to vary considerably according to species.

The use of voided urine temperature in the determination of basal body temperature

The temperature of freshly voided urine has been shown to be a reliable predictor of body temperature. This relationship was confirmed for the measurement of BBT. A method was described for patients to obtain their BBT in a way that they may find more convenient than obtaining either oral or rectal temperature. The BBT graph patterns generated from the temperature of freshly voided urine closely paralleled those generated by oral temperature.