Relationship between Ca2+ sparklets and sarcoplasmic reticulum Ca2+ load and release in rat cerebral arterial smooth muscle

Yukari Takeda, Matthew A. Nystoriak, Madeline Nieves-Cintrón, Luis F. Santana, Manuel F. Navedo

Research output: Contribution to journalArticlepeer-review

19 Scopus citations

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 languageEnglish (US)
Pages (from-to)2285-2294
Number of pages10
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume301
Issue number6
DOIs
StatePublished - Dec 2011
Externally publishedYes

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)

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