The effects of pregnancy and parturition on phosphorus metabolites in rat uterus studied by 31P nuclear magnetic resonance.

Abstract

SUMMARY1. Concentrations of phosphorus metabolites and intracellular pH have been measured in non-pregnant, late-pregnant and post-partum rat uterus using 31P nuclear magnetic resonance (31P n.m.r.). Intact uterine tissue was superfused with oxygenated de-Jalon solution at 4, 20 or 37 TC while inside the n.m.r. spectrometer.2. The phosphocreatine concentration [PCr], was higher and the inorganic phosphate concentration [Pi], lower than values determined by chemical analysis of extracts from both pregnant and non-pregnant rat uterus.[PCr] was 1-4-fold greater in late-pregnant than in non-pregnant rat uterus.3. Following parturition, large changes were observed in [PCr], [Pi] and in an unidentified metabolite in the phosphomonoester (PME) region ofthe n.m.r. spectrum. The time course of the recovery of these metabolites to prepregnant values was determined. The [PCr] remained below the non-pregnant value for at least 1 week post-partum and the [Pi] was elevated, compared to the non-pregnant value, during this period. More rapid changes were seen in the [PME], which doubled on day 0 post-partum but almost returned to its non-pregnant value on day 1 post-partum. 4. No significant difference was observed between intracellular pH values in late-pregnant and non-pregnant rat uterus; however, there was a large acid shift following parturition. Intracellular pH depended upon the temperature at which the tissue was maintained.5. The effect of muscular work during parturition was investigated by comparing Caesarian-sectioned uteri with uteri which had undergone normal parturition. Uteri examined 1 day after Caesarian operation showed no differences in metabolite levels from normal, 1 day post-partum uteri. 6. We conclude that concentrations of phosphorus metabolites depend upon the physiological state of the uterus. We suggest that the changes following parturition are not a consequence of the mechanical work performed by the uterus, but must be caused by some other event associated with parturition such as hormonal changes.

Developmental and gestational changes of phosphoethanolamine and taurine in rat brain, striated and smooth muscle

“…31P NMR spectroscopy, it is necessary to discuss how our findings relate to those in previous studies. In uterine smooth muscle and brain tissue, phosphoethanolamine was considered to be the major contributor to a large peak in "P NMR spectra (Dawson & Wray, 1985;Tofts & Wray, 1985). Subsequent work confirmed that this peak is due to phosphoethanolamine (Brenton, Garrod, Krywawych, Reynolds, Bachelard, Cox & Morris, 1985;Phoenix & Wray, 1994).…”

“…In a previous study, we showed that the increase in phosphoethanolamine concentration had not occurred 2-4 h postpartum, but by 6 h postpartum it had significantly increased. It was still elevated 12 h postpartum but had fallen 48 h postpartum (Dawson & Wray, 1985;Phoenix & Wray, 1994). The rise in phosphoethanolamine level while the uterus dramatically reduces in size (involution) suggests it may have a role in this process.…”

“…The stimulus is believed to be hormonal rather than mechanical, as similar changes occurred in uteri whether fetuses were delivered vaginally or by caesarian section. It was suggested that the changes in phosphoethanolamine concentration were related to postpartum reorganization of the uterus, including changes in cell size and hence membrane area (Dawson & Wray, 1985). However, it is not known whether the increase after parturition is specific to the uterus or whether similar changes occur in other tissues.…”

“…However, it is not known whether the changes dtiring development are specific to the brain and the heart or whether elevated levels of phosphoethanolamine and taurine occur in many tissues during neonatal life compared with adults. Furthermore, phosphoethanolamine has been shown to be present in adult rat uterus and its concentration increases briefly after parturition (Dawson & Wray, 1985). The stimulus is believed to be hormonal rather than mechanical, as similar changes occurred in uteri whether fetuses were delivered vaginally or by caesarian section.…”

An in vivo study of the effects of ischaemia on uterine contraction, intracellular pH and metabolites in the rat.

“…Peaks were identified on the basis of their resonance positions. Relative metabolite concentrations were obtained from integration of the peaks and corrected for effects of signal saturation using previously obtained factors (Dawson & Wray, 1985). To quantify the metabolite concentrations, a value for ATP under control conditions (1P8 mM) obtained in a previous study (Dawson & Wray, 1985) …”