Human bronchial smooth muscle (HBSM)

Human bronchial smooth muscle (HBSM) is a specialized contractile tissue located within the walls of the human respiratory tract, primarily responsible for regulating airway diameter and airflow resistance. Under physiological conditions, HBSM maintains airway tone through a balance of excitatory and inhibitory inputs from the autonomic nervous system and local paracrine factors (National Center for Biotechnology Information, 2023). In pathological states such as asthma and chronic obstructive pulmonary disease (COPD), HBSM undergoes significant structural changes, including hypertrophy and hyperplasia, which contribute to airway hyperresponsiveness and persistent airflow obstruction (Journal of Applied Physiology, 2019). Although HBSM is a tissue rather than a single molecular target, it serves as the primary site of action for major classes of respiratory drugs, including beta-2 adrenergic agonists and muscarinic antagonists (StatPearls, 2023). These drugs act on specific receptors expressed on the HBSM cell membrane to induce relaxation and alleviate bronchoconstriction. Furthermore, HBSM cells contribute to airway inflammation and remodeling by secreting various cytokines and extracellular matrix components, making them a complex focal point for therapeutic intervention (American Journal of Respiratory and Critical Care Medicine, 2020).

Other names

Bronchial smooth muscle cellsAirway smooth muscleHBSMC

Pharmacological agents modulate airway tone by targeting G-protein coupled receptors on the HBSM cell surface, such as beta-2 adrenergic receptors (agonism) to increase cAMP or muscarinic M3 receptors (antagonism) to decrease intracellular calcium (StatPearls, 2023).