Spatial and temporal aspects of calcium sparks in porcine tracheal smooth muscle cells

Christina M. Pabelick, Y. S. Prakash, Mathur S. Kannan, Gary C. Sieck

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


Spontaneous, localized intracellular Ca2+ concentration ([Ca2+](i)) transients (Ca2+ sparks) in skeletal, cardiac, and smooth muscle cells are thought to represent Ca2+ release through ryanodine-receptor (RyR) channels. In porcine tracheal smooth muscle (TSM) cells, ACh induces propagating [Ca2+](i) oscillations that also represent Ca2+ release through RyR channels. We used real-time confocal imaging to examine the spatial and temporal relationships of Ca2+ sparks to propagating [Ca2+](i) oscillations in TSM cells. Ca2+ sparks within an intracellular region displayed different spatial Ca2+ distributions with every occurrence. The amplitudes of Ca2+ sparks within a region were approximately integer multiples of the smallest response. However, across different regions, the attributes of Ca2+ sparks varied considerably. Individual sparks were often grouped together and coupled across adjacent regions. Fusion of individual sparks produced large local elevations in [Ca2+](i) that occasionally triggered a propagating [Ca2+](i) wave. The incidence of sparks was increased by ryanodine and caffeine but was unaffected by removal of extracellular Ca2+. Exposure to ACh triggered repetitive, propagating [Ca2+](i) oscillations that always originated from loci with a high spark incidence. The [Ca2+](i) oscillations disappeared with the removal of ACh, and Ca2+ sparks reappeared. We conclude that agonist-induced [Ca2+](i) oscillations represent a spatial and temporal integration of local Ca2+-release events through RyR channels in TSM cells.

Original languageEnglish (US)
Pages (from-to)L1018-L1025
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Issue number5 21-5
StatePublished - Nov 1999


  • Ryanodine
  • Sarcoplasmic reticulum
  • Second messenger

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology


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