A 32-year-old woman had abdominal surgery, after which she complains about difficulty in urination. Cholinomimetic stimulation with bethanechol or neostigmine is beneficial in relieving post-operative urinary retention. Neostigmine and bethanechol in moderate doses are likely to have different effect on?

Because neostigmine acts on the cholinesterase enzyme, which is situated at all cholinergic synapses, neostigmine increases acetylcholine effects at nicotinic and muscarinic junctions. Bethanechol is a directly acting drug that activates muscarinic receptors whether the nerve supply is present or not. The muscarinic receptors on vascular endothelial cells are not innervated and respond only to direct-acting drugs.