The Finkleman Preparation DEMO

Isoprenaline is a β₁, β₂ non-selective beta-adrenergic agonist causing relaxation of the intestine, an effect which is reveresed by propranolol a beta-adrenergic receptor antagonist. Phenylephrine, a selective α₁ alpha-adrenergic agonist, also relaxes the intestine, an effect reversed by the alpha-adrenergic receptor antagonist phentolamine. Tyramine, a nor-epinephrine releasing agent, also relaxes the intestine, an effect which is partially blocked by imipramine. The results suggest that the relaxation of the intestine is mediated by both alpha- and beta-adrenergic receptors.