Abstract
Ca+ sparklets are subcellular Ca2+ signals produced by the opening of sarcolemmal L-type Ca2+ channels. Ca2+ sparklet activity varies within the sarcolemma of arterial myocytes. In this study, we examined the relationship between Ca2+ sparklet activity and sarcoplasmic reticulum (SR) Ca2+ accumulation and release in cerebral arterial myocytes. Our data indicate that the SR is a vast organelle with multiple regions near the sarcolemma of these cells. Ca2+ sparklet sites were located at or <0.2 μm from SR-sarcolemmal junctions. We found that while Ca2+ sparklets increase the rate of SR Ca2+ refilling in arterial myocytes, their activity did not induce regional variations in SR Ca2+ content or Ca2+ spark activity. In arterial myocytes, L-type Ca2+ channel activity was independent of SR Ca2+ load. This ruled out a potential feedback mechanism whereby SR Ca2+ load regulates the activity of these channels. Together, our data suggest a model in which Ca2+ sparklets contribute Ca2+ influx into a cytosolic Ca2+ pool from which sarco(endo)plasmic reticulum Ca2+-ATPase pumps Ca2+ into the SR, indirectly regulating SR function.
Original language | English (US) |
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Pages (from-to) | 2285-2294 |
Number of pages | 10 |
Journal | American Journal of Physiology - Heart and Circulatory Physiology |
Volume | 301 |
Issue number | 6 |
DOIs | |
State | Published - Dec 2011 |
Externally published | Yes |
Keywords
- L-type Ca channels
- Ryanodine receptors
- Total internal reflection fluorescence microscopy
ASJC Scopus subject areas
- Physiology
- Physiology (medical)
- Cardiology and Cardiovascular Medicine
- Medicine(all)