Experimental Observations on the Energy Metabolism of Human Placenta

Abstract

Summary Oxygen consumption of histologically abnormal placentae was reduced but the effect on the fetus probably depends on the timing of the abnormality. A reduced placental respiratory rate, whether accompanied by no obvious histological change, or with the “senescent” changes of postmaturity, or by damage due to rehsus isoimmunization was associated with an adverse effect on fetal growth or wellbeing. Rotenone, antimycin A and cyanide, all inhibitors of mitochondrial electron transfer, markedly decreased the endogenous respiration of both normal and pathological placentae. Respiration was also reduced by from 35 per cent to 60 per cent by oligomycin, whereas it was increased by as much as 70 per cent by 2,4‐dinitrophenol. Oligomycin inhibition of endogenous respiration was largely offset by 2,4‐dinitrophenol. The results obtained showed that: (i) placental respiration was decreased in all the pathological conditions studied, (ii) the organization of the mitochondrial respiratory chain of placental cells might be similar to that of other normal tissues and (iii) placental respiration was coupled to energy conservation reactions both in normal and pathological conditions.