Introduction: The aim of this investigation was to point to the influence of minerals and total osmolality on regulation and secretion of prolactin in decidual tissue of the placenta and the role of prolactin in regulation of osmotic processes across the fetoplacental membrane.
Material and methods: Explants for the tissue culture have been obtained from pregnant women with normal pregnancy and delivery, between the 277 and 282 days of gestation. The investigation consisted of 4 repeated experiments. The parietal decidua and the corresponding chorion were separated from the amnion, rinsed in salt solution and cut into explants 0.2 g of weight. After a 2-hour period of preincubation in the control medium, 12 explants were incubated in the media of altered mineral and osmotic properties, whereas the 13-th in the control medium. Concentrations of prolactin following the 3-hour incubation in the medium was estimated by immunoenzymologic procedures.
Results: During the 3-hour incubation, the control explants secreted on average 75.4 +/- 5.23 micrograms/l of prolactin in the experiment repeated 4 times. The changes of Na+, Cl-, K+, Mg++, P- and HCO3- concentrations and of the total osmolality have not significantly influenced the synthesis of prolactin. In the medium with no Ca++, the value of secreted prolactin was 26.7 +/- 3.34 micrograms/l (p < 0.001); increase of the Ca++ concentration has not influenced the synthesis of prolactin. In the medium with increased concentration of H+ (pH = 7.00), the prolactin concentration was 50.9 +/- 2.9 micrograms/l (p < 0.001).
Conclusion: The minerals--Na+, Cl-, K+, Mg++, P-, HCO3- and the total osmolality do not significantly influence the synthesis of prolactin in decidual-chorionic tissue. Certain quantities of Ca++ and optimal concentration of H+ are necessary for the synthesis of prolactin (PRL).