Potentiation of cholinergic activity with pyridino[1,2-a]imidazo[5,4-b]indole: In vitro studies

1. 1. Effects of a novel imidazoindole derivative on cholinergic function were studied in isolated tissue preparations. 2. 2. The compound demonstrated a dose-dependent (10 −11–10 −9) potentiation (20–60%) of acetylcholine induced tension in guinea pig ileal tissue. 3. 3. Increases in the size of end-plate potentials and nerve evoked muscle twitches were observed in frog nerve-skeletal muscle preparations. 4. 4. Cholinesterase activity was not inhibited. 5. 5. The results suggest that the compound has actions at the post-synaptic muscarinic receptor complex in smooth muscle and causes pre-synaptic increases in ACh release at the neuromuscular junction.