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Measurement of Calcium Fluctuations Within the Sarcoplasmic Reticulum of Cultured Smooth Muscle Cells Using FRET-based Confocal Imaging
Published on: June 20, 2016
Relationship between the sarcoplasmic reticulum and the plasma membrane
Cheng-Han Lee1, Damon Poburko, Kuo-Hsing Kuo
1The iCAPTUR4E Center, University of British Columbia, St Paul's Hospital, Vancouver, Canada.
Novartis Foundation Symposium
|August 8, 2002
Summary
Ionic interactions between plasma membrane (PM) and sarcoplasmic reticulum (SR) drive smooth muscle function. Calcium (Ca2+) waves in vascular smooth muscle rely on specific ion channels and exchangers for sustained activity and homeostasis.
Area of Science:
- Physiology
- Cell Biology
- Biochemistry
Background:
- Ionic interactions between the plasma membrane (PM) and sarcoplasmic reticulum (SR) are vital for smooth muscle activation and homeostasis.
- Repetitive asynchronous Ca2+ waves are common in vascular smooth muscle signaling.
- Understanding these ionic mechanisms is key to smooth muscle physiology.
Purpose of the Study:
- To elucidate the ionic mechanisms underlying Ca2+ signaling in vascular smooth muscle.
- To investigate the roles of specific ion channels and exchangers in Ca2+ wave propagation and maintenance.
- To explore the interplay between the PM and SR in regulating intracellular Ca2+.
Main Methods:
- Studied Ca2+ signaling in rabbit inferior vena cava smooth muscle.
- Investigated Ca2+ release via inositol trisphosphate receptors (InsP3R).
- Examined the function of the Na+/Ca2+-exchanger (NCX) and non-specific cation channels.
Main Results:
- Ca2+ waves are initiated by InsP3R-mediated release and propagated by regenerative release.
- Sustained Ca2+ oscillations depend on reverse mode NCX activity, driven by Na+ entry.
- Non-specific cation channels contribute to depolarization and voltage-gated Ca2+ channel activation.
- Sarcoplasmic-endoplasmic reticulum Ca2+-ATPase (SERCA) refills the SR, completing the cycle.
- At rest, SR and PM interactions reverse, facilitating Ca2+ extrusion via NCX.
Conclusions:
- PM-SR ionic interactions are critical for smooth muscle Ca2+ signaling dynamics.
- The Na+/Ca2+-exchanger plays a dual role in Ca2+ homeostasis and signaling.
- Ca2+ transport occurs at PM-SR junctions across narrow spaces, integrating cellular Ca2+ handling.
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