Lacinilene C methyl ether (LCME) constricts tracheal smooth muscle

Lacinilene C methyl ether (LCME) is a constituent of the cotton plant and has been implicated as a causative agent of byssinosis. The effect of synthetic LCME on the behavior of isolated strips of canine tracheal smooth muscle (TSM) was examined in tissue bath experiments. LCME (0.64-6.6 x 10(-4) M) caused slowly developing but strong and sustained contractions of TSM strips. Blockade of acetycholine, 5-hydroxytryptamine (5-HT), and histamine H1 receptors with atropine, methysergide, and pyrilamine, respectively, had no effect on constrictions induced by LCME. In contrast, the calcium channel antagonist, verapamil, significantly reduced the response to LCME. Moreover, addition of the beta receptor agonist, isoproterenol, at the peak of LCME-induced contractions relaxed tissues in a concentration-dependent manner. We conclude that LCME elicits contraction of TSM by enhancing the movement of calcium through potential-dependent channels of smooth muscle cell membranes. This mechanism of action does not require activation of specific membrane receptors for acetylcholine, 5-HT, and histamine.