Characterisation of leukotriene receptors on rat lung strip

The leukotriene receptor(s) present on rat lung strip have been characterised using the natural agonists, a selective mimetic, and potent (cysLT1) selective leukotriene receptor antagonists. Leukotriene C4 and leukotriene D4 displayed comparable contractile potencies whilst leukotriene E4 was less potent. However, both leukotriene D4 and leukotriene E4 were found to be partial agonists relative to leukotriene C4. Responses to all three leukotrienes were competitively antagonised by ICI 198615 (1-((2-methoxy-(4-phenylsulfonyl)-aminocarbonyl)-phenyl) methyl)-1H-indazol-6-yl) carbonic acid cyclopentyl ester), SK&F 104353 (2-(R)-hydroxy-3(S)-(2-carboxyethylthio)-3-(2-[8-phenyloctyl ]- phenyl)propanoic acid, and MK571 (+/-(E)-3-[3-[2-(7-chloro-2-quinolin-yl)ethenyl]-phenyl)- ([3-(dimethylamino)-3-oxopropyl]thio]methyl]thio]thio]propanoic acid) with comparable affinities irrespective of the agonist used. This indicates that rat lung contains a homogeneous population of leukotriene receptors and that they are of the CysLT1 type.