Regional differences in energy charge of the pregnant human uterus regardless of functional status in comparison with the non-pregnant uterus

Abstract

The energy status of the cell is mainly dependent on adenine nucleotides and can be expressed as energy charge (EC). EC is known to be kept at narrow limits near 0.90 under normal conditions in most cells. We recently reported remarkably low EC values in the human uterus under apparent steady-state conditions. The present paper is an extension of previous work. It shows that EC varies in different regions of the uterus in that the isthmic part in pregnant women displays a higher EC than the fundus of the uterus. There were no intergroup differences between non-pregnant and term pregnant women, nor between those who were in active normal labour, dysfunctional labour or those who were not in labour at all. On the other hand, EC in uterine muscle of post-menopausal women showed a significantly lower EC value. Human uterus seems to manage its metabolic requirements under different functional conditions in spite of low ATP and EC values. This suggests that ATP occurs in sufficient amounts to pertinent enzyme reactions, especially ATPases, which means Km values adapted for this unusually low ATP concentration.