The enzymatic reactions are described by which delta4-3-oxosteroids, specially testosterone, are inactivated in rat liver. The delta4-3-oxosteroid-5 alpha-reductase in liver microsomes was studied intensively and it was found that it is an enzyme system. The 5 alpha-reduction of testosterone with NADPH or with NADH depends upon different enzymes or enzyme systems.
In a group of 15 cases the cortisol concentrations were determined in fetal and maternal plasma during labour and after delivery. In maternal plasma the levels were about twice as high as in fetal plasma and rose up to more than 1000 mug/l during labour (x = 639 +/- 222). After delivery the concentrations decreased. In fetal plasma, cortisol increased during labour from x = 173 +/- to x = 276 +/- 75 at the time of delivery and decreased to x = 106 +/- 36 within the first 23 hours. In a second group of 20 cases maternal and umbilical cord blood and blood of the newborn during the first 28 hours after delivery were analyzed. The values were in the same ranges as in the first group. Extremely high maternal levels were not correlated to higher fetal values. The cortisol levels of postmature children did not significantly differ from those of normal babies.
The following enzymes were determined in the serum and plasma of man, dog and rat: alanine aminotransferase, asparate aminotransferase, alkaline phosphatase, lactate dehydrogenase and alpha-hydroxybutyrate dehydrogenase. The enzyme assays were performed on an Eppendorf-Enzymautomat 5010 using optimised conditions at 25 degrees C. The enzyme-activities changed by variable amounts during standing of the blood. This concerned mainly lactate dehydrogenase, alpha-hydroxybutyrate dehydrogenase and aspartate aminotransferase in the serum of the rat. In human serum and in dog serum, and in the plasma of man, dog and rat this effect was only less pronounced.
Yoshida-Ascites tumour cells grown with a deficiency of Mg show an increased passive permeability. This results in an accelerated efflux of Na+. The uptake of aminobutyric acid is decreased, while its release is unchanged. The uptake and release of alpha-methylglucopyranoside are unchanged. In the cells grown with a deficiency of Mg, the concentration of cyclic AMP is slightly increased. The addition of dibutyryl cyclic AMP results in similar but smaller changes in the cellular concentration of cations, to those found in Mg deficiency. It is suggested that the effects of Mg deficiency result from the action of cyclic AMP and/or an increase in the Ca concentration of the cell.
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