For my study biomedical sciences, I'm writing an essay about the drug isoprenaline. After reading a lot of papers, it is still unclear for me what the exact molecular mechanism of action of isoprenaline is. Does isoprenaline have an effect on the catalytic activity, the stabilisation/destabilisation of the receptor or a metabolic effect for example?
Isoprenaline (isoproteronol) is an agonist of beta1 adrenergic receptors, meaning that it causes the receptors to respond as if exposed to norepinephrine (noradrenaline), activating adenylate cyclase which produces cAMP, resulting in cardiac stimulation.
Isoprenaline is a pure beta-1 and beta-2 agonist. As others state, the beta-1 effect in the heart which is positively linked to adenyl cyclase increases cAMP hydrolysis from ATP. cAMP will activate PKA with phosphorylates calcium and sodium channels in the open conformation and potassium channels in the closed conformation. This will allow depolarization in nodal cells (calcium) and myocardial cells (sodium, calcium) and limit hyperpolarization in nodal and myocardial cells (potassium). Net effect: increased in chronotropy and inotropy (faster rate, more forceful contraction, respectively). Pharmacology is a beautiful subject.
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