Propranolol is a sympatholytic non-selective beta blocker. Sympatholytics are used to treat hypertension, anxiety and panic. It was the first successful beta blocker developed. Propranolol is often used by musicians and other performers to prevent stage fright. It has been taken by surgeons to reduce their own innate hand tremors during surgery. Propranolol is a non-selective beta blocker, that is, it blocks the action of epinephrine and norepinephrine on both β1- and β2-adrenergic receptors. It has little intrinsic sympathomimetic activity (ISA) but has strong membrane stabilizing activity. Research has also shown that propranolol has inhibitory effects on the norepinephrine transporter and/or stimulates norepinephrine release. Since propranolol blocks β-adrenoceptors, the increase in synaptic norepinephrine only results in α-adrenergic activation, with the α1-adrenoceptor being particularly important for effects observed in animal models.
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