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Assessment of Calcium Sparks in Intact Skeletal Muscle Fibers
Published on: February 24, 2014
Calcium sparklets in arterial smooth muscle.
Luis F Santana1, Manuel F Navedo, Gregory C Amberg
1Department of Physiology and Biophysics, University of Washington School of Medicine, Box 357290, Seattle, WA 98195, USA. santana@u.washington.edu
Clinical and Experimental Pharmacology & Physiology
|January 25, 2008
Summary
Voltage-dependent, L-type Ca2+ channels (LTCC) form Ca2+ sparklets in arterial myocytes. Their activity, modulated by protein kinase C alpha, influences vascular function and blood pressure regulation.
Area of Science:
- Cardiovascular Physiology
- Molecular Cell Biology
- Biophysics
Background:
- Voltage-dependent, L-type Ca2+ channels (LTCC) are critical for arterial smooth muscle contraction, impacting blood pressure.
- The precise spatial arrangement and functional states of LTCC in arterial myocytes remain unclear.
Purpose of the Study:
- To investigate the spatial organization and activity patterns of functional LTCC in arterial myocytes.
- To elucidate the mechanisms underlying different modes of Ca2+ sparklet activity and their physiological relevance.
Main Methods:
- Utilized total internal reflection fluorescence and swept-field confocal microscopy to visualize Ca2+ dynamics.
- Analyzed Ca2+ sparklet activity, distinguishing between low- and high-activity modes.
- Investigated the role of protein kinase C alpha (PKCa) and protein phosphatases 2A/2B in modulating LTCC activity.
Main Results:
- Observed that single or clustered LTCC openings generate local intracellular calcium elevations termed Ca2+ sparklets.
- Identified two distinct modes of Ca2+ sparklet activity: infrequent openings of solitary LTCC ('low activity') and sustained openings of LTCC clusters associated with PKCa ('persistent').
- Demonstrated that regional differences in PKCa and opposing phosphatase activity influence Ca2+ sparklet activity within myocytes.
Conclusions:
- Ca2+ sparklets, generated by Cav1.2 channels, are a key Ca2+ signal in arterial myocytes.
- The bimodal nature of Ca2+ sparklet activity, influenced by PKCa, plays a significant role in regulating local and global intracellular calcium.
- These findings suggest a novel mechanism for vascular function regulation through spatially organized LTCC activity.
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