Related Experiment Video
Updated: Jul 6, 2026
07:55
Pressure Controlled Ventilation to Induce Acute Lung Injury in Mice
Published on: May 5, 2011
Relationships between adenosine, cyclic nucleotides, and xanthines in asthma
The Journal of Allergy and Clinical Immunology
|October 1, 1986
Summary
Methylxanthines are used for asthma treatment, but their exact mechanism remains unclear. Research suggests multiple actions beyond phosphodiesterase inhibition and adenosine receptor antagonism contribute to their therapeutic effects.
Area of Science:
- Pharmacology
- Respiratory Medicine
- Biochemistry
Background:
- Methylxanthines, including theophylline, have a long history in asthma management.
- The precise molecular mechanisms underlying their bronchodilator effects are not fully elucidated.
- Key proposed mechanisms, such as phosphodiesterase inhibition and adenosine receptor antagonism, have limitations in explaining therapeutic efficacy.
Purpose of the Study:
- To explore the multifaceted mechanisms of action for methylxanthines in asthma treatment.
- To evaluate the relevance of phosphodiesterase inhibition and adenosine receptor antagonism.
- To identify additional pathways contributing to the beneficial effects of methylxanthines.
Main Methods:
- The study reviews existing literature on methylxanthine pharmacology in asthma.
- It analyzes the dose-dependency and specificity of phosphodiesterase inhibition.
- It examines the role of adenosine receptor antagonism in the context of asthma pathophysiology.
Main Results:
- Phosphodiesterase inhibition by methylxanthines is primarily observed at toxic doses.
- Adenosine receptor antagonism is a plausible mechanism, particularly for theophylline, but does not explain enprofylline's action.
- Enprofylline's efficacy suggests mechanisms beyond phosphodiesterase and adenosine antagonism.
Conclusions:
- The therapeutic benefits of methylxanthines in asthma likely involve a combination of actions.
- Additional contributing factors include adrenaline release, modulation of cell calcium, inhibition of prostaglandin synthesis, and improved diaphragmatic function.
- Further research is needed to fully delineate the complex pharmacology of methylxanthines in respiratory diseases.
Related Concept Videos
01:30Adrenergic Agonists: Direct-Acting Agents
Drugs that mimic the action of endogenous catecholamines like noradrenaline and adrenaline are called adrenergic agonists or sympathomimetics. Based on their mechanism of action, sympathomimetics can be classified as direct-, indirect-, or mixed-acting sympathomimetics. Direct-acting adrenergic agonists activate adrenoceptors without affecting presynaptic neurons, making them independent of neuronal catecholamine-depleting agents like reserpine and guanethidine.
These agents can be classified...
These agents can be classified...
01:28Adrenergic Agonists: Mixed-Action Agents
Mixed-action adrenergic agonists, like ephedrine and pseudoephedrine, directly and indirectly affect adrenergic receptors. These agents stimulate adrenoceptors and indirectly release stored neurotransmitters, amplifying the adrenergic response.
Ephedrine and pseudoephedrine lack a catecholamine group, making them less susceptible to degradation by metabolic enzymes. They have increased oral bioavailability and lipophilicity, resulting in a longer duration of action. Their response is reduced by...
Ephedrine and pseudoephedrine lack a catecholamine group, making them less susceptible to degradation by metabolic enzymes. They have increased oral bioavailability and lipophilicity, resulting in a longer duration of action. Their response is reduced by...
01:18Adrenergic Agonists: Therapeutic Classification
Adrenergic agonists can be classified based on their therapeutic uses and mechanisms of action. They serve various purposes in clinical applications.
Vasopressor or pressor agents: They increase blood pressure and function as cardiac stimulants. Examples include endogenous catecholamines (norepinephrine and dopamine) and synthetic agents (phenylephrine).
Bronchodilators: β2-agonists can relax bronchial muscles and widen airways. They are commonly used for treating obstructive pulmonary...
Vasopressor or pressor agents: They increase blood pressure and function as cardiac stimulants. Examples include endogenous catecholamines (norepinephrine and dopamine) and synthetic agents (phenylephrine).
Bronchodilators: β2-agonists can relax bronchial muscles and widen airways. They are commonly used for treating obstructive pulmonary...
01:30Adrenergic Agonists: Therapeutic Uses
Adrenergic agonists have diverse therapeutic uses across various medical conditions and emergencies.
Emergency and Intensive Care Unit (ICU) applications: Pressor agents increase blood pressure, heart rate, and contractility in shock and organ failure situations. Dopamine can induce vasodilation and stimulate adrenoceptors. Endogenous catecholamines are effective in treating cardiogenic shock. α2-agonists like clonidine can reverse anesthesia-induced hypertension.
Allergies and anaphylaxis:...
Emergency and Intensive Care Unit (ICU) applications: Pressor agents increase blood pressure, heart rate, and contractility in shock and organ failure situations. Dopamine can induce vasodilation and stimulate adrenoceptors. Endogenous catecholamines are effective in treating cardiogenic shock. α2-agonists like clonidine can reverse anesthesia-induced hypertension.
Allergies and anaphylaxis:...
01:24Antiasthma Drugs: Methylxanthines
Theophylline, a member of the methylxanthine class of bronchodilators, has long been used in asthma management. While its exact mechanism of action is not fully understood, it is believed to have multiple effects on various cellular processes.
Theophylline is thought to inhibit phosphodiesterase enzymes, increasing intracellular levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). This rise in cAMP and cGMP concentrations stimulates cardiac function,...
Theophylline is thought to inhibit phosphodiesterase enzymes, increasing intracellular levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). This rise in cAMP and cGMP concentrations stimulates cardiac function,...
01:28Asthma I: Introduction
Asthma is a chronic inflammatory disorder of the airways characterized by variable airflow obstruction and heightened bronchial responsiveness to a wide range of triggers. The underlying inflammation leads to airway swelling, mucus hypersecretion, and smooth muscle constriction, all of which narrow the airway lumen and impede airflow. Clinically, asthma presents with recurrent episodes of wheezing, shortness of breath, chest tightness, and coughing, symptoms that typically vary in intensity and...