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KMID : 0376219730100030885
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Chonnam Medical Journal
1973 Volume.10 No. 3 p.885 ~ p.893
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Catabolim of Adenosine Diphosphate Ribose in Human Placenta
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Abstract
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Incubation of adenosine diphosphate ribose (ADPR) and adenosine monophosphate (AMP) with human term placentas from normal vaginal deliveries resulted in the formation of adenosine, inosine, and hypoxanthine with disappearance of ADPR and AMP. In this conversion, inosine monophosphate was not involved as an intermediate.
The conversion to adenosine of AMP, which was formed from ADPR by placental ADPR pyrophosphohydrolase, was catalyzed by placental alkaline phosphatase and 5’-nucleotidase. Alkaline phosphatase was responsible for more than 50% of the AMP-hydrolyzing activity present in the placental, homogenates. It was found that placental 5´-nucleotidase was markedly inhibited by ADP added in vitro, suggesting that placental formation of adenosine from AMP be regulated by 5 -nucleotidase.
The activities of placental, enzymes hydrolyzing ADPR and AMP were assayed at their respective optimal pH, and were found to be in decreasing order of alkaline phosphatase>acid phosphatase> ADPR pyrophosphohydrolase >5´ -nucleotidase.
From these results, it is suggested that in the placenta nicotinamide adenine dinucleotide (NAD) is converted to adenosine through the intermediate formation of ADPR and AMP The possible participation of these compounds in the regulation of placental blood flow was also discussed.
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