Endothelin A-receptors and the coronary circulation

Abstract

<p> <span style="font-size:10.0pt;"><span style="font-family:Verdana;">We review the role of endothelin (ET) A-receptors (R) on the coronary circulation. ET-1 maintains the normal coronary artery tone. ET-1 plasma levels are increased during and after coronary angioplasty and this increase is related to myocardial ischaemia rather than to mechanical artery injury. ET</span>_{<span style="font-family:Verdana;">A</span>}<span style="font-family:Verdana;">R antagonists inhibit coronary artery vasoconstriction induced by ET release after coronary angioplasty in humans. ET promotes neointimal formation and ET</span>_{<span style="font-family:Verdana;">A</span>}<span style="font-family:Verdana;">R antagonism has been shown to inhibit restenosis after angioplasty in the animal model but not in humans. ET</span>_{<span style="font-family:Verdana;">A</span>}<span style="font-family:Verdana;">R blockade increases coronary blood flow, dilates distal coronary arterial segments and decreases coronary vascular resistance. Coronary collaterals are less sensitive than other coronary vessels to ET-1. ET</span>_{<span style="font-family:Verdana;">A</span>}<span style="font-family:Verdana;">R blockade decreases collateral blood flow and, consequently, perfusion of the ischemic myocardium.</span></span> </p