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

Imagen de Manuel F Navedo
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TítuloRelationship between Ca2+ sparklets and sarcoplasmic reticulum Ca2+ load and release in rat cerebral arterial smooth muscle.
Publication TypeJournal Article
Year of Publication2011
AutoresTakeda, Y, Nystoriak, MA, Nieves-Cintrón, M, Santana, LF, Navedo, MF
JournalAm J Physiol Heart Circ Physiol
Volume301
Issue6
PaginationH2285-94
Date Published2011 Dec
ISSN1522-1539
Palabras claveAnimals, Calcium, Calcium Channels, L-Type, Calcium Signaling, Cerebral Arteries, Luminescent Proteins, Microscopy, Confocal, Microscopy, Fluorescence, Muscle, Smooth, Vascular, Myocytes, Smooth Muscle, Protein Sorting Signals, Rats, Rats, Sprague-Dawley, Recombinant Fusion Proteins, Ryanodine Receptor Calcium Release Channel, Sarcolemma, Sarcoplasmic Reticulum, Sarcoplasmic Reticulum Calcium-Transporting ATPases, Time Factors, Transfection
Abstract

Ca(+) sparklets are subcellular Ca(2+) signals produced by the opening of sarcolemmal L-type Ca(2+) channels. Ca(2+) sparklet activity varies within the sarcolemma of arterial myocytes. In this study, we examined the relationship between Ca(2+) sparklet activity and sarcoplasmic reticulum (SR) Ca(2+) 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. Ca(2+) sparklet sites were located at or <0.2 μm from SR-sarcolemmal junctions. We found that while Ca(2+) sparklets increase the rate of SR Ca(2+) refilling in arterial myocytes, their activity did not induce regional variations in SR Ca(2+) content or Ca(2+) spark activity. In arterial myocytes, L-type Ca(2+) channel activity was independent of SR Ca(2+) load. This ruled out a potential feedback mechanism whereby SR Ca(2+) load regulates the activity of these channels. Together, our data suggest a model in which Ca(2+) sparklets contribute Ca(2+) influx into a cytosolic Ca(2+) pool from which sarco(endo)plasmic reticulum Ca(2+)-ATPase pumps Ca(2+) into the SR, indirectly regulating SR function.

DOI10.1152/ajpheart.00488.2011
Alternate JournalAm. J. Physiol. Heart Circ. Physiol.
PubMed ID21984539
PubMed Central IDPMC3233819
Grant ListHL-085686 / HL / NHLBI NIH HHS / United States
HL-085870 / HL / NHLBI NIH HHS / United States
HL-098200 / HL / NHLBI NIH HHS / United States
R01 HL098200 / HL / NHLBI NIH HHS / United States
T32-HL-07828 / HL / NHLBI NIH HHS / United States