Abstract
The purpose of this report is to present data on c-AMP dependent protein kinase activity in the human placenta which is considered to be related to the process of fetal growth. The c-AMP dependent protein kinase activity in fresh human placental chorionic tissues obtained at each gestational trimester was measured with c-AMP concentration, RNA and DNA concentrations and aromatizing enzyme activity. The results are as follows:
1. The specific activities of c-AMP dependent protein kinase (p moles ATP / mg protein/minute) in the human placental chorionic tissues were 44.67±5.29, 45.24±9.13 and 34.19±4.95 in the first, second and third trimesters, respectively.
2. The c-AMP concentrations in the human placental chorionic tissues in each trimester showed 56.45±9.26, 59.90±15.51 and 22.54±4.59 p moles/mg protein, respectively.
3. RNA concentrations (mg/g wet tissue) in the human placental chorionic tissues in each trimester were 2.48±0.20, 2.57±0.58 and 2.63±0.42, respectively; the corresponding figures fo rDNA were 1.62±0.34, 2.49±0.34 and 2.92±0.45. The RNA/DNA ratio was 1.61±0.10, 1.08±0.17 and 0.89±0.15, respectively.
4. Aromatizing enzyme activities (products n moles/flask/30minutes) in the human placental chorionic tissues in each trimester were 2.75±0.70, 3.40±0.11 and 4.86±0.85, respectively, in its total homogenate with nuclei involved, and 1.16±0.30, 0.90±0.33 and 1.80±0.70, respectively, in cell-free homogenate without nuclei.
From these results, it is considered that each placental chorionic cell augments its function in the tissue as necessary, although it becomes smaller, reducing the weight with the process of pregnancy. Furthermore, it is suggested that the c-AMP-c-AMP dependent protein kinase system may play an important role in control of active transport of materials and protein metabolism.
