Betaadrenerge

Betaadrenerge refers to the beta-adrenergic system, including the beta-adrenergic receptors and their ligands, which mediate part of the sympathetic nervous system response. The term encompasses endogenous catecholamines like epinephrine and norepinephrine as well as synthetic agents that stimulate or block these receptors.

The beta-adrenergic receptor family comprises three main subtypes: β1, β2, and β3. β1 receptors are mainly in the heart and kidneys, where their activation increases heart rate, myocardial contractility, and renin release. β2 receptors are abundant in the lungs, vascular and bronchial smooth muscle, liver, and skeletal muscle, producing bronchodilation, vasodilation in certain beds, and metabolic effects. β3 receptors are primarily in adipose tissue and regulate lipolysis and thermogenesis. Receptors in each tissue generate distinct physiological responses that contribute to overall cardiovascular, respiratory, and metabolic regulation.

All beta receptors are G protein-coupled receptors that typically couple to Gs proteins, stimulating adenylate cyclase and increasing cyclic AMP, which activates protein kinase A and produces tissue-specific effects. The overall response depends on receptor distribution, endogenous tone, and interacting signaling pathways.

Pharmacologically, beta-adrenergic agents include endogenous agonists (epinephrine, norepinephrine) and synthetic drugs such as isoproterenol (non-selective β agonist) and dobutamine (β1-selective). Beta blockers (β-adrenergic antagonists) like propranolol (non-selective) and metoprolol (β1-selective) are used for hypertension, angina, arrhythmias, and heart failure. β2 agonists such as albuterol are common bronchodilators in asthma and COPD. Chronic exposure can lead to receptor up- or down-regulation, with clinical implications for tolerance and dosing.