Interaction between adenosine and allergen or compound 48/80 on lung parenchymal strips from actively sensitized...

We have investigated the effect of mast cell activation induced by immunological and non-immunological stimuli on the sensitivity to adenosine of parenchymal strips prepared from lungs removed from Brown Norway (BN) rats actively sensitized to ovalbumin. Strips responded to ovalbumin with a biphasic contractile response. Responses to adenosine were markedly increased 30 min after ovalbumin. The first phase of the response to ovalbumin was abolished by the 5-hydroxytryptamine (5-HT)2 receptor antagonist, methysergide and unaffected by the cysteinyl leukotriene receptor antagonist, iralukast. The second phase was abolished by iralukast and unaffected by methysergide. The response to adenosine was markedly reduced by methysergide but not significantly altered by iralukast. Compound 48/80 (condensation product of N-methyl-p-methoxyphenylethylamine with formaldehyde) induced methysergide-sensitive contractions of the parenchymal strip and potentiated adenosine; the augmented response to adenosine was blocked by methysergide. Thus, activation of mast cells in the lung by either immunological or non-immunological stimuli results in augmentation of the mast cell-mediated contractile response to adenosine.