Related Experiment Video
Updated: Aug 8, 2026
10:30
Immunocompetent Alveolus-on-Chip Model for Studying Alveolar Mucosal Immune Responses
Published on: May 31, 2024
Lung surfactant secretion by interalveolar Ca2+ signaling
Hideo Ichimura1, Kaushik Parthasarathi, Jens Lindert
1Lung Biology Laboratory, Department of Physiology and Cellular Biophysics, College of Physicians and Surgeons, Columbia University, St. Luke's-Roosevelt Hospital Center, New York, NY 10019, USA.
Summary
Interalveolar communication coordinates surfactant secretion in the lung's smallest respiratory units. Calcium signals, transmitted via connexin43 (Cx43), regulate type 2 cell secretion in adjacent alveoli, suggesting coordinated acinar function.
Area of Science:
- Pulmonary physiology
- Cellular biology
- Biophysics
Background:
- The acinus, composed of alveoli clusters, is the lung's distal respiratory unit.
- The role of interalveolar communication in coordinating surfactant secretion within the acinus remains unclear.
Purpose of the Study:
- To investigate whether interalveolar communication coordinates surfactant secretion in the rat lung acinus.
- To elucidate the mechanisms underlying this communication.
Main Methods:
- Real-time digital imaging and photo-excited calcium (Ca2+) uncaging in isolated, blood-perfused rat lungs.
- Loading alveolar cells with Ca2+ indicators (NP-EGTA-AM, fluo 4) and secretion markers (LysoTracker green).
- Selective UV illumination to uncage Ca2+ and observe cellular responses.
Main Results:
- Uncaging Ca2+ increased cytosolic Ca2+ concentration ([Ca2+]cyt) and induced type 2 cell secretion in the targeted alveolus.
- Conducted [Ca2+]cyt increases triggered type 2 cell secretion in neighboring alveoli, demonstrating interalveolar communication.
- Connexin43 (Cx43)-inhibiting peptides blocked these conducted responses, implicating Cx43 in the communication.
Conclusions:
- Cx43-dependent, interalveolar Ca2+ signals regulate surfactant secretion in adjacent alveoli.
- This interalveolar communication likely facilitates coordinated acinar function, crucial for efficient gas exchange.
More Related Videos
Related Concept Videos
01:05Breathing
The process of breathing, inhaling and exhaling, involves the coordinated movement of the chest wall, the lungs, and the muscles that move them. Two muscle groups with important roles in breathing are the diaphragm, located directly below the lungs, and the intercostal muscles, which lie between the ribs. When the diaphragm contracts, it moves downward, increasing the volume of the thoracic cavity and creating more room for the lungs to expand. When the intercostal muscles contract, the ribs...
01:26Alveoli and Alveolar Ducts
The respiratory zone of the human body, which stands in contrast to the conducting zone, comprises the structures that actively participate in the exchange of gases. The initiation of this zone is marked by the terminal bronchioles converging into respiratory bronchioles, the tiniest bronchiole classification. The respiratory bronchioles give way to the alveolar ducts that opens into a congregation of alveoli. Actively involved in gas exchange, alveoli resemble tiny sacs similar to clusters of...
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...
01:17Pulmonary Cycle: Exhalation
In terms of human respiration, the act of expelling air, known as exhalation (or expiration), operates on the principle of pressure gradients. During expiration, the pressure within the lungs exceeds that of the surrounding atmosphere. Under normal conditions, quiet breathing involves passive exhalation and is free of muscular contractions. This is because the exhalation process is driven by the natural elastic recoil of the lungs and chest wall, both of which have an inherent tendency to...
01:27Feedback Regulation of Calcium Concentration
Calcium is an essential signaling molecule required for various cellular functions. Calcium pumps and ion channels on cell and organellar membranes, such as those on the endoplasmic reticulum (ER), regulate calcium concentrations inside the cell. They remain closed, keeping the cytosolic calcium levels low at a resting state.
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
01:24Pressure Relationships in Thoracic Cavity
Breathing, otherwise known as pulmonary ventilation, is the process of air movement into and out of the lungs. The main mechanisms propelling pulmonary ventilation are atmospheric pressure (Patm), intra-pulmonary (Ppul ) or intra-alveolar pressure (Palv) within the alveoli, and intrapleural pressure (Pip) within the pleural cavity.
Breathing Mechanisms
Both intra-alveolar and intrapleural pressures rely on specific lung properties. The ability to breathe—allowing air to enter the lungs during...
Breathing Mechanisms
Both intra-alveolar and intrapleural pressures rely on specific lung properties. The ability to breathe—allowing air to enter the lungs during...