I’m planning to investigate the M2 receptor function in brain. Arecaidine but-2-ynyl ester tosylate is believed as a selective M2 receptor agonist, however, it is now discontinued (from Tocris). I have not found an effective alternative agonist for M2 receptor yet. Who knows muscarinic acetylcholinergic receptor-2 agonist at commercial availability? Thank you!