BQ123, an ETA Receptor Antagonist, Attenuates Endothelin-1-Induced Vasoconstriction in Rat Pulmonary Circulation

Abstract

Endothelin-1 (ET-1) is a potent endogenous vasoactive peptide whose role in regulation of vascular tone is unclear. BQ123 is a recently described ET_A receptor antagonist which may be useful in further investigation of the physiologic and pathophysiologic significance of ET-1. To test its efficacy in the pulmonary circulation, the vascular response to exogenous ET-1 with and without BQ123 was assessed in rat pulmonary artery (PA) rings and salt-perfused lungs. In both main and distal (250–350 μm ID) PA rings, BQ123 significantly attenuated ET-1-induced contractility, but was more effective in the larger vessels. Likewise, BQ123 significantly blunted ET-1-induced vasoconstriction in perfused lungs by A receptor.