Adrenal Endocrine and Circulatory Responses to Acute Prolonged Asphyxia in Surviving and Non-Surviving Fetal Sheep near Term
A previous study on the effects of acute prolonged asphyxia produced some interesting results on the changes in blood flow of surviving and non-surviving fetal sheep near term (Jensen et al. 1985, 1987). It revealed that fetal circulatory centralization during acute asphyxia is a rapid process in which blood flow to peripheral organs falls and that to central organs increases after 1 and 2 min asphyxia respectively. That study also demonstrated that the ability of the fetal circulation to maintain centralization throughout asphyxia is essential for survival, because circulatory decentralization on the nadir of asphyxia always preceded fetal death. These observations and the fact that in non-surviving fetuses adrenal blood flow failed to increase during asphyxia suggested that adrenal function and fetal survival of acute prolonged asphyxia might be interrelated. However, since non-surviving fetuses were more asphyxic than surviving fetuses, the possibility also had to be considered that severe hypoxaemia and acidaemia may have direct adverse effects on the maintenance of circulatory centralization and hence may reduce the fetus’ chances of surviving asphyxia.
KeywordsAdrenal Cortex Peripheral Organ Circulatory Centralization Zona Glomerulosa Zona Fasciculata
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