Elevation of fetoplacental vascular resistance by chronic hypoxia in isolated blood perfused rat placenta

Abstract

In isolated rat placenta chronic hypoxic exposure causes a small increase in fetoplacental vascular resistance during high perfusion flows of physiological salt perfusate. No elevation was found in basal perfusion flows. We expected that perfusion with more viscous fluid will increase differences between normoxia and chronic hypoxia. Rats were exposed to normobaric hypoxia (10% O2) during the last week of the 3‐week pregnancy. One day before expected delivery the animals were anaesthetized with Thiopental (50 mg/kg i.p.). We dually perfused an isolated rat placenta with homologous blood at a constant flow rate 1 ml/min. We found significantly elevated fetoplacental basal vascular resistance to flow in chronically hypoxic rats. Vascular resistance was measured as a relationship of vascular perfusion pressure to continually rising flow (P/Q). The slope of the P/Q line was higher in the hypoxic than the normoxic rats. The pressure axis intercepts with P/Q line did not differ. We conclude that chronic hypoxia elevates resistance of fetoplacental vessels in isolated blood perfused rat placenta.Supported by 2nd Faculty of Medicine, Charles University and Czech Science Foundation 305/08/0108.