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Experiments were performed to determine whether cells from human chorion can synthesize and release progesterone. Cells were isolated from term chorion laeve by collagenase-DNAse digestion and incubated in RPMI-1640 medium. Freshly isolated cells contained 9.9 +/- 1.1 ng progesterone/10(6) cells, and released 72.0 +/- 7.1 ng/10(6) cells X 24 h in the absence of precursors. When 25-hydroxycholesterol (25HC) served as a precursor, progesterone release into the medium was concentration and time dependent from 1-20 micrograms/ml up to 8 h. When pregnenolone served as a precursor, progesterone secretion followed Michaelis-Menten kinetics (Km = 6.7 microM; maximum velocity, 1.02 nmol/10(6) cells X h). In the presence of 25HC (20 micrograms/ml), progesterone release increased significantly on exposure to cholera toxin (1 microgram/ml), methylisobutylxanthine (0.1 mM), forskolin (0.1 mM), or (Bu)2cAMP (1 mM). Cells maintained in culture released progesterone when fetal calf serum (10%) or 25HC served as precursors. These studies show that trophoblasts from fetal membranes can synthesize and release progesterone from endogenous and exogenous precurors and support the suggestion that cAMP is an important mediator in this process.

It is known that renin is present in fetal membranes, with the highest concentration in the chorion laeve (reflected chorion). The purpose of this study was to identify and localize renin in human chorion laeve. Indirect immunofluorescent analysis, using antiserum against pure human kidney renin, revealed a single layer of cells in the chorion with strongly positive fluorescence. The presence of atrophic villi in this layer together with other morphological evidence indicate that the cells which are positive for renin are cytotrophoblasts. Isolated cells were prepared from the chorion by collagenase digestion, followed by filtration and density gradient centrifugation on Percoll. The isolated cells also showed a positive reaction with the immunofluorescent technique. Control experiments with nonimmune serum did not show fluorescent cells. Biochemical analysis using RIA of angiotensin I generated from sheep substrate indicated that most of the renin activity in the isolated cells was present as inactive renin (activated by trypsin). The presence of renin in trophoblastic cells may be of significance in local cardiovascular regulation, events associated with parturition, or pathophysiological manifestations of trophoblastic disease.

In confirmation of our previous studies, lowering the temperature of the incubation medium from 37 C to 0 C caused a 20–30-fold increase in vasopressin release from the isolated bovine neurohypophysis. Rewarming the gland by transferring the preparation from 0 C to 37 C triggered an even greater release of vasopressin. The rewarming effect also occurred when glands were brought from 10 C or 15 C to 37 C. The effect of rewarming was not affected by calcium (2.2 mM) or by DNP (0.5 mM). Studies on the time course of the cold temperature-induced release of vasopressin indicated that the rewarming effect was not due to a delayed effect of the cold. Parallel with the output of vasopressin during rewarming, there was a large increase in LDH efflux. This suggests that changing the temperature from 0 C to 37 C may damage the cell membrane, which results in an increased leakage of cell constituents. This study also suggests that caution should be taken in altering the temperature of isolated pituitary glands; the c...

Reduction of the temperature from 37 C to 18, IS, 10 or 0 C evoked a graded release of vasopressin from bovine neurohypophyses incubated in vitro in Locke's solution. Cold temperature was still effective in releasing vasopressin when Na was replaced by Li, K, Cs or Tris in the incubation medium but was inhibited by high concentrations of Ca, Mg or La. Low temperature caused the simultaneous release of vasopressin, ATP and protein from neurohypophyses in stoichiometric amounts comparable to their relative proportions in neurosecretory granules. At the same time, the release of cytoplasmic markers, LDH and K, was decreased. These results suggest that cold-induced release of vasopressin occurs by the process of exocytosis and not by generalized cell damage. In parallel with studies on coldinduced muscle contraction, cold-induced vasopressin release is more prominent in Ca free solution, is inhibited by replacement of NaCl with sucrose, and is potentiated by caffeine.These results suggest that mobilization of...