Which mode of action describes how theophylline affects cyclic AMP?

Theophylline is primarily known for its role as a bronchodilator in the treatment of respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD). Its mechanism of action involves the inhibition of phosphodiesterase enzymes, which are responsible for breaking down cyclic AMP (cAMP). By preventing the breakdown of cAMP, theophylline effectively increases its levels within cells, leading to enhanced relaxation of bronchial smooth muscle and improved airflow.

Elevated cAMP levels have positive effects on bronchial dilation and can also exert anti-inflammatory effects. This mechanism contributes to the overall therapeutic effects of theophylline and helps to alleviate symptoms of airway obstruction. Therefore, the correct understanding of the mode of action of theophylline is that it prevents the breakdown of cyclic AMP, thus allowing for prolonged signaling and action within the respiratory tract.