Located on postsynaptic effector cells Beta1-adrenergic receptors located primarily in the heart Beta2- located in bronchioles, arterioles, and visceral organs Results in o Bronchial, GI& uterine smooth muscle relaxation o Glycogenolysis (breakdown of glycogen to glucose o Cardiac stimulation Cause: Increase force of contraction Increased heart rate Increased conduction through the av node Beta 2 Bronchodilation Uterine relaxation (stop labor) Glycogenolysis in the liver Increased renin secretion in the kidneys Toxicity: treatment is to give a rapid-acting sympatholytic drug (Esmolol) Synthetic catecholamine: Isoproterenol Dobutamine Phenylephrine Direct acting - Synthetic catecholamine acts just like the real deal- binds directly to the receptor and causes a physiologic response Indirect-acting: Synthetic catecholamine cause the release of catecholamine from the storage sites (vesicles) in the nerve endings. Mixed-acting: Synthetic catecholamine ;directly stimulates the receptor by binding to it and indirectly stimulates the receptor by causing the release of stored neurotransmitters from the vesicles in the nerve endings. Uses: A or B2 Epinephrine and dipivefrin: reduction of intraocular pressure and mydriasis (pupil dilation); treatment of open-angle glaucoma Temporary relief of conjunctival congestion (red eyes) A receptors o Epinephrine o Phenylephrine (Nasal Decongestant) relaxes smooth bronchial muscles o Naphazoline o Tetrahudrozoline Nasal decongestant – A1 stimulation o Constriction of dilated arterioles and reduction of nasal blood flow thus decreasing congestion Alpha side effect CNS: Headache, restlessness, excitement, insomnia, euphoria CV: Palpitations, tachycardia, vasoconstriction, hypertention Other: Anorexia, dry mouth, nausea, vomiting, taste changes Beta Side effects
CNS: Mild tremors, headache, nervousness, dizziness, CV:Increased HR, palpitations, fluctuations in BP Other: Sweating, nausea, vomiting, muscle cramps Interactions: – Anesthetic agents – Trycyclic antidepressants – MSOIs – Antihistamines – Thyroid preparations – Antihypertensives Salmeterol i s indicated for prevention of bronchospasms, not management of acute symptoms Overuse of nasal decongestants may cause rebound nasal congestion or ulcerations Avoid OTC or other medications because of possible interactions. Isoproterenol: may turn sputum or saliva pink Chapter 18 Adrenergic-Blocking Agents Have the opposite effect of adrenergic agents also known as Sympatholytics = inhibit or LYSE sympathetic neurotransmitters. Vocabulary: Acrocyanosis : decreased amount of oxygen delivered to the extremities, causing the feet or hands to turn blue. (phenoxybenzamine treats this) Angina : Paroxysmal (sudden) chest pain caused my myocardial ischemia.
- Winter '16
- heart rate, Adrenergic receptor