Related Experiment Video
Updated: Jul 17, 2026
09:00
Calcium Imaging of Odor-evoked Responses in the Drosophila Antennal Lobe
Published on: March 14, 2012
Calcium and avian intrapulmonary chemoreceptor response to CO2
S C Hempleman1, S X Egan, J Q Pilarski
11Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona 86011-5640, USA. steven.hempleman@nau.edu
Journal of Applied Physiology (Bethesda, Md. : 1985)
|August 12, 2006
Summary
Calcium influx via L-type channels inhibits intrapulmonary chemoreceptors (IPC) in reptiles and birds. Chloride channels modulate IPC responses to carbon dioxide, impacting breathing regulation.
Area of Science:
- Comparative Physiology
- Respiratory Neurobiology
- Chemoreception
Background:
- Intrapulmonary chemoreceptors (IPC) in birds and reptiles are vital for respiratory control.
- IPC exhibit sensitivity to carbon dioxide (CO2) and spike frequency adaptation (SFA).
- The role of calcium (Ca2+) in modulating IPC function and CO2 responsiveness is not fully understood.
Purpose of the Study:
- To investigate the influence of transmembrane Ca2+ fluxes and Ca2+-related channels on IPC function.
- To determine if Ca2+ mechanisms modulate CO2 responsiveness and SFA in single-unit IPC.
- To elucidate the specific roles of L-type Ca2+ channels, Ca2+-activated K+ channels, and chloride channels.
Main Methods:
- Single-unit electrophysiological recordings from avian IPC.
- Pharmacological manipulation using channel blockers (cadmium, cobalt, nifedipine, charybdotoxin, apamin, niflumic acid) and activators (BAY K 8644).
- Assessment of IPC discharge and spike frequency adaptation (SFA) under varying inspired Pco2 conditions.
Main Results:
- Blockade of Ca2+ channels (Cd2+, Co2+, nifedipine) increased IPC discharge; L-type Ca2+ channel activation (BAY K 8644) decreased it, indicating an inhibitory Ca2+ influx.
- Blockade of Ca2+-activated K+ channels (charybdotoxin, apamin) increased IPC discharge but did not affect SFA.
- Blockade of chloride channels (niflumic acid) attenuated the IPC CO2 response by reducing discharge at low Pco2 and increasing it at high Pco2.
Conclusions:
- Ca2+ influx through L-type Ca2+ channels exerts an inhibitory effect on IPC afferent discharge and CO2 sensitivity.
- Spike frequency adaptation in IPC is not mediated by apamin- or charybdotoxin-sensitive Ca2+-activated K+ channels.
- Chloride channels, targeted by niflumic acid, play a significant role in modulating IPC CO2 responses.
Related Concept Videos
01:16Calmodulin-dependent Signaling
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
01:23Physiological Control of Respiration
Introduction
Breathing, a seemingly passive process, is regulated by the respiratory center in the brainstem. This center coordinates the involuntary control of respirations, which means it occurs without conscious effort, ensuring a smooth and uninterrupted pattern.
Regulation of Ventilation
The body maintains ventilation by monitoring levels of carbon dioxide (CO2), oxygen (O2), and hydrogen ion concentration (pH) in the arterial blood. Among these factors, the level of CO2 plays a crucial...
Breathing, a seemingly passive process, is regulated by the respiratory center in the brainstem. This center coordinates the involuntary control of respirations, which means it occurs without conscious effort, ensuring a smooth and uninterrupted pattern.
Regulation of Ventilation
The body maintains ventilation by monitoring levels of carbon dioxide (CO2), oxygen (O2), and hydrogen ion concentration (pH) in the arterial blood. Among these factors, the level of CO2 plays a crucial...
01:24External and Internal Respiration
External respiration occurs in the lungs, and it is the first step in the journey of oxygen inside the body. When we inhale, oxygen enters our lungs and diffuses across the thin alveolar membrane. The alveoli are tiny, air-filled sacs that provide a vast surface area for gas exchange. Oxygen in the alveoli has a higher partial pressure (105 mmHg) than in the adjacent pulmonary capillaries (40 mmHg), establishing a pressure gradient. As a result, oxygen molecules move from the alveoli into the...
01:19Carbon Dioxide Transport in the Blood
Carbon dioxide (CO2) transport in the blood is critical to human physiology. On average, our body cells produce around 200 mL of CO2 per minute, precisely the quantity expelled by the lungs. This process involves the transportation of CO2 from the tissue cells to the lungs in three primary forms.
Forms of CO2 Transport
1. Dissolved in plasma: A small percentage (7-10%) of CO2 is transported and dissolved directly in the plasma.
2. Carbaminohemoglobin: Just over 20% of CO2 is chemically bound to...
Forms of CO2 Transport
1. Dissolved in plasma: A small percentage (7-10%) of CO2 is transported and dissolved directly in the plasma.
2. Carbaminohemoglobin: Just over 20% of CO2 is chemically bound to...
01:31Chemical Factors Affecting Respiration Centers
Chemical factors such as changing CO2, O2, and H+ levels in arterial blood play a critical role in influencing respiration depth and rates. These variations are detected by chemoreceptors—specialized sensors located in two primary body areas. Central chemoreceptors are found throughout the brain stem, including the ventrolateral medulla, while peripheral chemoreceptors are located in the aortic arch and carotid arteries.
CO2 has a potent influence on respiration and is strictly regulated. Under...
CO2 has a potent influence on respiration and is strictly regulated. Under...
01:18Respiratory Regulation of Acid-Base Balance
Respiratory compensation is a vital physiological process that stabilizes blood plasma pH by regulating the partial pressure of carbon dioxide (PCO2), a key determinant of pH levels. Most carbon dioxide in the blood dissolves and converts into carbonic acid (H2CO3). It dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3⁻). There is also an inverse relationship between PCO2 and pH.
When carbon dioxide levels increase in the blood, more H+ and HCO3⁻ are produced, leading to a...
When carbon dioxide levels increase in the blood, more H+ and HCO3⁻ are produced, leading to a...