Lactate distribution in culture medium of human myometrial biopsies incubated under different conditions

Abstract

It is generally believed that a relationship exists between muscle fatigue and intracellular accumulation of lactate. This reasoning is relevant to obstetrical issues. Myocytes in uterus work together during labor, and the contractions need to be strong and synchronized for a child to be delivered. At labor dystocia, the progress of labor becomes slow or arrested after a normal beginning. It has been described that, during labor dystocia, when the force of the contractions is low, the uterus is under hypoxia, and anaerobic conditions with high levels of lactate in amniotic fluid dominate. The purpose of this study was to examine whether myometrial cells are involved in the production of lactate in amniotic fluid and whether there are differences in production and distribution of lactate in cells incubated under aerobic and anaerobic conditions. We also wanted to elucidate the involvement of specific membrane-bound lactate carriers. Women undergoing elective caesarean section were included. Myometrial biopsies from uteri were collected and subjected to either immunohistochemistry to identify lactate carriers or in vitro experiments to analyze production of lactate. The presence of lactate carriers named monocarboxylate transporters 1 and 4 was verified. Myometrial cells produced lactate extracellularly, and the lactate carriers operated differently under anaerobic and aerobic conditions; while being mainly unidirectional under anaerobic conditions, they became bidirectional under aerobic conditions. Human myometrial cells produced and delivered lactate to the extracellular medium under both anaerobic and aerobic conditions. The delivery was mediated by lactate carriers.

Lactate in Amniotic Fluid: Predictor of Labor Outcome in Oxytocin-Augmented Primiparas’ Deliveries

“…A close correlation has been described between lactate produced by the uterine unit and the level of lactate in amniotic fluid (AFL) [21]. High levels of AFL are shown to be over-represented in dystocic deliveries compared to deliveries with a normal progress of labor [21–25].…”

“…High levels of AFL are shown to be over-represented in dystocic deliveries compared to deliveries with a normal progress of labor [21–25]. A new, non-invasive method has been developed that makes it possible to detect the AFL level in a small sample of amniotic fluid collected from the vaginal pouch and analysed at the bedside in the delivery room.…”

“…A new, non-invasive method has been developed that makes it possible to detect the AFL level in a small sample of amniotic fluid collected from the vaginal pouch and analysed at the bedside in the delivery room. Levels of AFL can be measured immediately and an answer provided within 15 seconds [21–25]. …”

Lactate produced during labor modulates uterine inflammation via GPR81 (HCA1)

“…During anaerobic conditions outward flow of lactate dominates over intracellular transport in mSMC. 34 Hence during labor lactate flows out of the mSMC to bind to membrane-bound GPR81, at concentrations consistent with the affinity of GPR81 for lactate (w5 mmol/L) 10 ; the inherently low affinity of GPR81 for its ligand is consistent with other GPCRs of the same family, notably GPR109A and GPR109B. 35 High uterine lactate concentrations as observed during parturition are not likely to be achieved under other physiological circumstances, which may restrict the role of GPR81 to labor only.…”

A pilot study to determine the feasibility of collecting amniotic fluid samples from women during labour and measuring amniotic fluid lactate at point of care

“…Measurement of lactate in amniotic fluid of labouring women may be a surrogate biochemical marker for labour dystocia [6-9] based on the reasonable hypothesis that dystocia is partly due to lactic acidosis of myometrial tissue [10]. Recent physiological studies on the effects of acidification of the uterus show human myometrium to be sensitive to changes in pH, and that accumulation of lactic acid in myometrium during contractions may reduce the strength of contractions [7,11].…”