Figure 2. Involvement of cholinergic and purinergic neuro-neuronal transmission underlying the ascending excitatory reflex.

A, brush stroking the mucosa (3 strokes; arrow) in the anal stimulating chamber elicited a synchronous contraction of the LM and CM in the oral recording chamber. B, addition of hexamethonium (Hex, 300 μm) to the intermediate chamber was without effect on ascending neuro-neuronal transmission. C, further addition of PPADS (10 μm) to the intermediate chamber abolished the ascending excitatory reflex to both muscle layers. D, in a different preparation, three control brush strokes to the mucosa elicited synchronous contractions of the two muscle layers. E, the addition of hexamethonium (300 μm) to the intermediate chamber attenuated ascending neuro-neuronal transmission. F, the further addition of α,β-methylene ATP (50 μm) abolished non-nicotinic ascending transmission to both muscles.