Biomedical subjects

S B Coade

Publications and source records attributed to S B Coade.

21 records · Page 2Linked to original sources

PubMedDate not supplied

Mechanical and metabolic viability of a placental perfusion system in vitro under oxygenated and anoxic conditions.

In vitro dual circuit perfusion of the placenta with well-oxygenated medium results in the continuous and stable consumption of oxygen and glucose over a 2-h perfusion period. This is reflected in a stable production of lactate and an energy charge which is higher at the end of the perfusion period than that seen in fresh placental tissue immediately after vaginal delivery. Anoxic perfusion causes an increase in glucose consumption which is more than twofold higher than that seen in the oxygenated perfusion, resulting finally in placental uptake of glucose not only from the maternal but also from the fetal circulation. Lactate production is increased during the anoxic perfusion, while the final tissue energy charge value lies between the values observed for fresh tissue and for the oxygenated perfusion. The shift to anaerobic metabolism shown by placental tissue in anoxic conditions enables continued functioning of the tissue over the 2-h perfusion period but it appears that under anoxic conditions the tissue may incur an energy debt not observed in oxygenated perfusions.

Adenine Nucleotides↗

PubMedDate not supplied

Human placental mitochondrial respiration and its regulation by adenine nucleotides.

Respiratory parameters were studied in mitochondria from human placenta. Respiratory control and ADP/O ratios were low in this preparation. The adenine nucleotide content of placental mitochondria was found to be only one quarter of that found for adult uterine muscle tissue mitochondria prepared in the same way. Loading placental mitochondria with adenine nucleotides by incubation in the presence of ATP produced increased respiratory control ratios but no improvement in ADP/O ratios. Our evidence is consistent with the developmental changes shown to occur in rat liver, in which an increased concentration of adenine nucleotides is responsible for changes in respiratory parameters.

Adenine Nucleotides↗

PubMedDate not supplied

Effect of a failure of energy supply on adenine nucleotide breakdown in placentae and other fetal tissues from rat and guinea pig.

The effects of ischaemia on adenylate energy charge of tissues from fetal rats and fetal guinea pigs were measured. Adult rat and guinea-pig tissues, as well as human placentae, were also studied. The largest differences observed were between the fetuses from different pregnant animals (P = 4.74 X 10(-15). Reductions in energy charge in placentae were slower than in other defined fetal tissues, especially brain. In the rat, an immature species at birth, greater 'stability' was observed in placentae of 14 days of gestation than near term at 20 days of gestation. As contrast, in the guinea pig, a mature species at birth, there was no difference in 'stability' in placenta or other fetal tissues between about 40 days of gestation and near term, about 60 days of gestation. In addition to these tissue and maturity effects in the fetus, it has been confirmed that fetal tissues are more 'resistant' than adult tissues to failures of energy supply. Concentrations of adenosine, uridine, guanosine and cytidine nucleotides in placenta show similar patterns in rats and guinea pigs. Fetal liver contains more uridine nucleotides and brain more cytidine nucleotides. It is suggested that the placenta retains an early fetal ability to maintain itself during ischaemia; this might be advantageous during parturition. Possible endocrine and other mechanisms 'damping' fetoplacental metabolism are linked with a discussion of the large maternal effect.

Adenine Nucleotides↗