Altered Potassium Channel Expression in the Human Placental Vasculature of Pregnancies Complicated by Fetal Growth Restriction

OBJECTIVE: Decreased activity of "oxygen-sensitive" potassium (K) channels reduces hypoxia-induced contraction of pulmonary vascular tissue. "Oxygen-sensitive" channels are present in the fetoplacental vasculature, where vascular resistance is thought to increase in fetal growth restriction (FGR). We assessed placental gene expression of K(V)2.1, K(V)9.3 and K(IR)6.1, three "oxygen-sensitive" K channels in normal pregnancy and FGR. METHODS: Biopsies were obtained from 12 normal pregnancies and 12 pregnancies complicated by FGR. Chorionic plate arteries and veins were dissected from the biopsies and a sample of placental tissue comprising chorionic plate and villus tissue was also collected. All samples were processed and analyzed using "real time" quantitative RT-PCR. RESULTS: K(V)2.1 and K(V)9.3 gene expression, in veins and placental homogenate, respectively, were increased in FGR. K(IR)6.1 gene expression was comparable in normal pregnancy and FGR samples. CONCLUSIONS: The gene expression of two voltage-gated K channels thought to be important for altered vascular reactivity following changes in oxygenation is increased in FGR.