Abstract
In human placenta, adenylate cyclase is activated by hormones like human chorionic gonadotropin, epinephrine, prostaglandins, luteinizing hormone and vasointestinal polypeptide. For the liver, the resultant second messenger adenosine 2′:3′-cyclic monophosphate (cAMP) is known to induce phosphoenol-pyruvate car-boxykinase (PEP-CK). So far there have been no reports concerning placental PEP-CK. - METHODS: 600 mg tissue of human term placentae was incubated in Earle's solution and amino acids by gassing with O2 and CO2 for 120 minutes. Dibutyryl-cAMP was added to a final concentration of 1 mM. PEP-CK and the other important gluconeogenic enzyme pyruvate carboxylase (PC) were determined in placental tissue by 14CO2 fixation method. - RESULTS: 1. The incubation elevated PC activity from 32.9 ± 15.9 uU/mg protein (mean ± S.D.) post partum to 81.6 ± 30.8 (n=6; p<0.05) and PEP-CK from 8.65 ± 4.0 to 233.6 ± 88.8 (n=5; p<0.05). 2. Dibutyryl-cAMP had no effect on PC (74.9 ± 19.6; n=6), but lowered PEP-CK to 59.1 ± 24.3 (n=5; p<0.05) . - CONCLUSIONS: 1. Placental PC is not subjected to hormonal regulation which is mediated by cAMP. 2. PEP-CK in placenta showed a pattern different from the liver: CAMP deinduced PEP-CK. This observation is in accordance with our previous findings of epinephrine action on placenta (I.Henrichs et al., Acta endocrin. 114, 36-37 (1987)). - Supported by DFG, He 1107/2.
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Henrichs, I., Kellner, M., Benz, R. et al. EFFECT OF CYCLIC AMP ON GLUCONEOGENIC ENZYMES IN HUMAN PLACENTA. Pediatr Res 23, 137 (1988). https://doi.org/10.1203/00006450-198801000-00217
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DOI: https://doi.org/10.1203/00006450-198801000-00217