Key result
Intrauterine exposure to lipopolysaccharide in fetal sheep suppressed cardiac contractility by ~40%, reduced cardiomyocyte numbers by ~25%, and increased infarct area 3.2-fold after ischemia.
Why the study?
Does intrauterine inflammation induced by LPS impair cardiac function and alter structure in preterm fetal sheep?
Does intrauterine inflammation induced by LPS impair cardiac function and alter structure in preterm fetal sheep?
Intrauterine inflammation in a preterm sheep model alters cardiac growth, suppresses contractile function, and increases vulnerability to ischemia/reperfusion injury.
May link fetal inflammation to cardiac vulnerability in preterm models; leaves open human translation and requires validation.
Intrauterine inflammation is a major contributor to preterm birth and has adverse effects on preterm neonatal cardiovascular physiology. Cardiomyocyte maturation occurs in late gestation in species such as humans and sheep. We tested the hypothesis that intrauterine inflammation has deleterious effects on cardiac function in preterm sheep which might be explained by altered cardiomyocyte proliferation and maturation. Pregnant ewes received an ultrasound-guided intra-amniotic injection of lipopolysaccharide (LPS) or saline 7 days prior to delivery at day 127 of pregnancy (term 147 days). Cardiac contractility was recorded in spontaneously beating hearts of the offspring, perfused in a Langendorff apparatus. Saline-filled latex balloons were inserted into the left ventricle (LV) and right ventricle (RV). Responsiveness to isoprenaline and stop-flow/reperfusion was assessed. In other experiments, hearts were perfusion-fixed, and cardiomyocyte nuclearity, volume and number were determined. β-Adrenoceptor mRNA levels were determined in unfixed tissue. In hearts of LPS-exposed fetuses, contractility in the LV and RV was suppressed by ~40% and cardiomyocyte numbers were reduced by ~25%. Immature mono-nucleated cardiomyocytes had lower volumes (~18%), whereas mature bi-nucleated cardiomyocyte volume was ~77% greater. Although basal coronary flow was significantly increased by 21±7% in LPS-exposed hearts, following ischaemia/reperfusion (IR), end-diastolic pressure was increased 2.4±0.3-fold and infarct area was increased 3.2±0.6-fold compared with those in controls. Maximum responsiveness to isoprenaline was enhanced by LPS, without an increase in β-adrenoceptor mRNA, suggesting altered second messenger signalling. Intrauterine inflammation altered cardiac growth, suppressed contractile function and enhanced responsiveness to stress. Although these effects may ensure immediate survival, they probably contribute to the increased vulnerability of organ perfusion in preterm neonates.
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Tare et al. (2014) studied Intrauterine inflammation. Intra-amniotic injection of lipopolysaccharide (LPS) vs. Saline was evaluated on Cardiac contractility and cardiomyocyte numbers. Intrauterine exposure to lipopolysaccharide in fetal sheep suppressed cardiac contractility by ~40%, reduced cardiomyocyte numbers by ~25%, and increased infarct area 3.2-fold after ischemia.
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