Progesterone, corticosteroids, and relaxin have been implicated in bringing about a reduction in resistance and increase in conduction in the respiratory passage due to reduced bronchomotor tone
and smooth muscle relaxation.
Beta blocker namely propranolol gives effects, which outlasted the stressful interval by several hours and did not usually include an increase in bronchomotor tone
Over a relatively brief periods, resistance may change with accumulating secretions or variations of bronchomotor tone
, and effective respiratory system compliance changes with body position.
improvement in lung function--as inflammation subsides, resting bronchomotor tone
changes and the airways spontaneously dilate; bronchodilator responses are often also better.
Inhaled anticholinergic drugs are also effective for COPD patients, since the pathogenesis of COPD is closely related to bronchomotor tone
, which reflects sympathetic and parasympathetic balance [3, 4].