Abstract 318: The Cardiotonic Bufodienolide Steroid Marinobufagenin Alters Messenger RNA Concentrations of Soluble Flt-1 in Human Brain Microvascular Endothelial Cell Monolayers

Abstract

Previous studies from this laboratory have provided evidence that, in a rat model of preeclampsia (PE), the cardiotonic bufodienolide, marinobufagenin (MBG), is not only a biomarker but an etiologic factor. Concentrations of MBG in blood and urine are increased in women with PE compared to those with normal pregnancies. Additionally, MBG has been determined in both in vivo and in vitro studies to cause vascular leak. Those studies included direct evidence that MBG causes hyperpermeability of endothelial monolayers. Because PE patients may exhibit neurologic abnormalities often associated with cerebral edema, we examined the effects of MBG on endothelial monolayers obtained from human brain microvasculature. Since PE has also been determined to alter concentrations of factors that affect angiogenesis, we investigated the effects of treatment with 10-8 M MBG on primary cultures of endothelial cells from human brain microvasculature on concentrations of mRNAs encoding the VEGF receptor called soluble Flt-1 (Flt-1 variant 2 mRNA) and Flt-1 mRNA variant 3, as well as NF kappa B (NFKB1), a substance often involved in tissue injury. MBG depressed the concentrations of Flt-1 mRNA within 2 h, with the largest effect (reduced to ½) at 12 h compared to vehicle treated controls. The effect was reversed at 24 h, when MBG-treated endothelial cells contained 2.4-fold higher Flt-1 mRNA. Throughout the time course, Flt-1 variant 3 and NFKB1 mRNA levels were unchanged. These studies are currently being extended with microarray analyses of the global transcriptome of MBG-treated and control cultures of endothelial cells from human brain microvessels.