Bradykinin and substance P potentiate acetylcholine-induced bronchospasm in guinea-pig.

The interaction of threshold doses of bradykinin (BK) and substance P (SP) with acetylcholine (ACh)-induced bronchospasm was investigated in anaesthetized guinea-pigs. The two peptides potentiated the ACh-induced bronchospasm, an effect which did not seem to depend on prostaglandin release. On the other hand, vagotomy abolished the capacity of BK and SP to potentiate the ACh-induced bronchospasm. The present data suggest a possible involvement of BK and SP in the genesis of airway hyperreactivity.