Stimulatory drugs on isolated heart

By Dr Sameh AM abdel-ghany

Alpha blockers

• Alpha 1 and alpha 2: phentolmaine, phenoxybenzamine and tolazoline.

• Alpha 1: prozosin, doxazosin and terazosin.

• Alpha 2: yohmbine

Beta blockers

• Beta1, beta2: propranolol• Beta 1: metoprolol and atenolol• Beta 2: butoxamine

Stimulation of isloated heart with sympathomimetics To increase cardiac contractilty with

Sympathomimetics: Stimulate B1 receptors : e.g • Adrenaline • Noradrenaline• Isoprenaline

Stimulation of heart with EpinephrineSteps:1. Inject Epinephrine produces ↑ in both HR and

contractility.2. Try other B1 stimulants e.g. Norepinephrine and

Isoprenaline3. Inject B1- Blocker e.g Propranolol 4. Inject Epinephrine rapidly before the action of

propranolol ends No effect of epinephrine5. Try other B1 stimulants e.g. Norepinephrine and

Isoprenaline after propranolol

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