Effects of novel leukotriene receptor antagonists in the isolated rat aorta

We screened 14 novel antagonists of the LTB4 and LTD4 receptors (also inhibitors of LTB4 synthesis) for their vasoactive properties in the isolated rat aorta. The compounds belong to three classes, e.g. quinoline (Q), phenetylamido (P), and resatophenone (R) derivatives. They are effectiveless in resting conditions and generally display a weak relaxing ability against contraction by either high K+ or α1 adrenoceptor activation, either in the presence or absence of a functional endothelium. There is little overlap with the generally lower concentration range where their anti-LT properties are already manifested. We could not find any correlation between any of the anti-LT properties and the vasorelaxant effects. Concerning the non-specific vasoactive properties, choice compounds of the examined groups could be further tested regarding the mechanisms of their relaxing effects. Given the many uncertainties concerning LT and vascular physiology, it may be worthy to proceed with this line of investigation.