Beta 2 agonist causes
**Core Concept**
Beta 2 agonists are a class of medications that stimulate the beta 2 adrenergic receptors in the body, leading to increased activity in the smooth muscle of the bronchi, uterus, and vascular smooth muscle. This results in bronchodilation, uterine relaxation, and vasodilation.
**Why the Correct Answer is Right**
Beta 2 agonists, such as salbutamol and albuterol, work by binding to the beta 2 adrenergic receptors on the surface of smooth muscle cells. This binding causes a conformational change in the receptor, which activates the Gs protein and increases the production of cyclic AMP (cAMP). The increased cAMP activates protein kinase A (PKA), which in turn phosphorylates and relaxes the smooth muscle cells, leading to bronchodilation and vasodilation.
**Why Each Wrong Option is Incorrect**
**Option A:** Beta 2 agonists do not primarily cause vasopressin release; that is a function of the renin-angiotensin-aldosterone system.
**Option B:** Beta 2 agonists do not primarily cause increased sympathetic tone; that is a function of the sympathetic nervous system.
**Option C:** Beta 2 agonists do not primarily cause increased parasympathetic tone; that is a function of the parasympathetic nervous system.
**Clinical Pearl / High-Yield Fact**
Beta 2 agonists should be used with caution in patients with pre-existing cardiovascular disease, as they can cause hypokalemia, tachycardia, and increased cardiac workload.
**Correct Answer: D. Increased cAMP production and smooth muscle relaxation**