Cysteinyl-leukotriene receptors in pulmonary vessels

Two categories of cysteinyl-leukotrienes have been proposed, namely, CysLT( 1) and CysLT(2). These receptors are found not only on the vascular smooth muscle but also on the endothelium. Activation of the receptor(s) on vascul ar smooth muscle provokes contraction whereas activation of the receptors:o n the endothelium produces contraction and/or relaxation. These endothelium dependent effects are to the release of both contractile and relaxant:fact ors derived from the endothelium. While factors derived from either the cyc looxygenase or nitric oxide pathways are involved, in some vascular prepara tions other mediators such as endothelin may be involved. However, in isola ted human pulmonary vascular preparations, this appears not to be the case and presently the nature and origin of the contractile factor remains to be established.