Figure 3

The non-specific nature of airway hyperreactivity and a convergent signalling pathway for spasmogens: hope for a novel therapy for asthma? ASM receives diverse excitatory inputs from the innervation, inflammatory cells, and the epithelium, all of which act through distinct receptors, but a common signalling pathway. In asthma, the smooth muscle exhibits increased sensitivity to a wide range of excitatory stimuli. The non-specific nature of airway hyperreactivity suggests that some post-receptor mechanism(s) within the smooth muscle per se is altered. Spasmogens act through a convergent signalling pathway involving Ca²⁺-handling and RhoA.