Inhibition of antigen- and calcium ionophore A23187-induced contractions of guinea pig isolated airways with 8-(diethylamino)octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8)

Both antigen- and calcium ionophore A23187-induced airways contractions are dependent on increased concentrations of intracellular calcium. Challenge of isolated tracheal spirals and parenchymal strips from sensitized guinea pigs with antigen or calcium ionophore A23187 in the presence of the intracellular calcium antagonist, 8-(diethylamino)octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8), resulted in significantly reduced contractions. The results demonstrated that TMB-8 inhibits events that are dependent on either mobilization of intracellular calcium (i.e. antigen) or entry of calcium from extracellular sources (i.e. calcium ionophore A23187). The efficacy of TMB-8 in this model suggests that intracellular calcium antagonists may be potentially useful in the therapy of asthma.