Related Experiment Video
Updated: Aug 11, 2026
10:20
In vitro Measurements of Tracheal Constriction Using Mice
Published on: June 25, 2012
Interaction between bronchoconstrictor stimuli on human airway smooth muscle
The Yale Journal of Biology and Medicine
|September 1, 1976
Summary
Histamine and methacholine together significantly reduce maximum flow rates in healthy individuals. This interaction on airway smooth muscle (ASM) highlights a potential mechanism influencing airway responses and suggests assessing drug effects before a deep breath is crucial.
Area of Science:
- Respiratory Physiology
- Pharmacology
- Pulmonology
Background:
- Histamine and methacholine are known bronchoconstrictors.
- Airway smooth muscle (ASM) plays a key role in regulating airway caliber.
- Previous studies suggest interactions between different stimuli on ASM.
Purpose of the Study:
- To investigate the combined effect of histamine and methacholine on airway function in humans.
- To explore the potential interaction between histamine and cholinergic stimuli on ASM.
- To evaluate the sensitivity of partial expiratory flow-volume (PEFV) curves versus maximum expiratory flow-volume (MEFV) curves in assessing drug effects.
Main Methods:
- Simultaneous aerosol administration of histamine and methacholine to healthy human subjects.
- Measurement of maximum flow rates using partial expiratory flow-volume (PEFV) curves.
- Comparison of PEFV curve results with those obtained from maximum expiratory flow-volume (MEFV) curves and drugs administered alone.
Main Results:
- Simultaneous administration of histamine and methacholine caused a pronounced decrease in maximum flow rates on PEFV curves.
- Individual administration of histamine or methacholine at the same concentrations resulted in minimal or no flow rate reduction.
- MEFV curves showed significantly less or no response to methacholine compared to PEFV curves.
Conclusions:
- A synergistic interaction exists between histamine and cholinergic stimuli on human airway smooth muscle (ASM).
- This histamine-cholinergic interaction at the ASM level may explain the effects of vagal blockade in certain experimental settings.
- Assessing drug effects on PEFV curves, particularly before a deep breath, is more sensitive than using MEFV curves.
Related Concept Videos
01:26Adrenergic Receptors: β Subtype
β-adrenoceptors have varied sensitivities towards adrenaline, noradrenaline, and isoprenaline. The order of agonist potency is as follows:
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...
Isoprenaline > Adrenaline > Noradrenaline
Neurotransmitter binding to these receptors causes activation of adenylyl cyclase resulting in increased concentrations of cAMP and modulation of calcium ion channels within the cell. They are further classified into β1, β2, and β3 subtypes.
β1-adrenoceptors: β1-adrenoceptors have equal affinities for...
01:20Asthma: Pathogenesis and Management
Asthma is a chronic pulmonary condition involving inflammation of the airways, hyper-reactivity, and reversible obstruction of the airways. This condition can significantly impact a person's quality of life, making breathing difficult and leading to distressing symptoms.
Asthma is classified as allergic and non-allergic. Allergens such as dust mites, pollen, and pet dander trigger allergic asthma, while factors like cold air, intense emotions, or exercise can induce non-allergic asthma.
Asthma is classified as allergic and non-allergic. Allergens such as dust mites, pollen, and pet dander trigger allergic asthma, while factors like cold air, intense emotions, or exercise can induce non-allergic asthma.
01:19Factors Affecting Pulmonary Ventilation
Besides the pressure difference between the external environment and the lungs, the airflow rate and ease of pulmonary ventilation are also influenced by three other factors: surface tension of the fluid in the alveoli, compliance of the lungs, and airway resistance.
Alveolar Surface Tension
The alveolar fluid lines the luminal surface of the alveoli and exerts a force called surface tension. This force is caused by the polar water molecules in the liquid being more strongly attracted to each...
Alveolar Surface Tension
The alveolar fluid lines the luminal surface of the alveoli and exerts a force called surface tension. This force is caused by the polar water molecules in the liquid being more strongly attracted to each...
01:20Chronic Obstructive Pulmonary Disease-II: Pathophysiology
Chronic Obstructive Pulmonary Disease (COPD) pathophysiology is intricate and multifaceted, involving a complex interplay of physiological processes. Understanding these mechanisms is crucial for effectively managing and treating COPD. Here is an in-depth look at the critical elements in the pathophysiology of COPD:
Chronic Inflammation
Chronic Inflammation
01:26Asthma-II: Pathophysiology and Classification
Asthma is a prevalent chronic respiratory condition marked by inflammation and hyperresponsiveness of the airways. Its pathophysiology involves complex interactions among inflammatory pathways, immune responses, and neural mechanisms.
Additionally, environmental and genetic factors play crucial roles in determining an individual's susceptibility to asthma and the severity of their condition.
Critical processes in asthma pathophysiology include:
Additionally, environmental and genetic factors play crucial roles in determining an individual's susceptibility to asthma and the severity of their condition.
Critical processes in asthma pathophysiology include:
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...