Subclass-specific receptors for sulfidopeptide leukotrienes.

Separate receptors for LTC4 and LTD4 have been identified and characterized by physiologic and radioligand binding criteria. LTD4 receptors appear to be plasma-membrane-associated and to display characteristics previously described for many hormone receptors, such as inhibition of agonist binding by guanine nucleotides and Na+, suggesting a postreceptor linkage to adenylate cyclase of an inhibitory nature. LTC4 receptors have a substantial subcellular distribution; agonist binding to the receptor is not influenced by monovalent ions or guanine nucleotides but is enhanced by divalent cations. Within these two major subclass receptors with specificity for LTC4 and LTD4, respectively, there is an additional heterogeneity in terms of affinities. It is considered likely that a third receptor mediates the distinct actions of LTE4 on a guinea pig tracheal spirals, where this agonist exhibits greater contractile potency than LTD4 and LTC4 and elicits hyperreactivity to histamine that is not a nonspecific response to a prior contraction.