Human Chorionic Plate Arteries Lack an Endothelium-Dependent Relaxation Response

Abstract

This study was designed to demonstrate that human chorionic plate arteries exhibit endothelium-dependent relaxation. Vessel ring segments (2mm long) were studied in a wire myograph system in which force and vessel dimensions were measured. The calcium ionophore A23187 (n = 10), or histamine (n = 2) was added to precontracted arteries in concentrations known to stimulate release of endothelium-derived relaxing factor(s) in umbilical vessels (10⁻⁸ M-10⁻⁶ M). A23187 did not cause relaxation of these arteries, while 10⁻⁵ M histamine enhanced contraction. The vessels exhibited concentration-dependent relaxation in response to the addition of nitric oxide (n = 3), and relaxed completely upon addition of 10⁻⁶ M sodium nitroprusside (n = 8), indicating a functional guanylate cyclase in the smooth muscle.