Signaling between SR and plasmalemma in smooth muscle: sparks and the activation of Ca2+-sensitive ion channels

Cell Calcium. 2003 Sep;34(3):211-29. doi: 10.1016/s0143-4160(03)00124-6.


Intracellular calcium ions are involved in the regulation of nearly every aspect of cell function. In smooth muscle, Ca2+ can be delivered to Ca2+-sensitive effector molecules either by influx through plasma membrane ion channels or by intracellular Ca2+ release events. Ca2+ sparks are transient local increases in intracellular Ca2+ that arise from the opening of ryanodine-sensitive Ca2+ release channels (ryanodine receptors) located in the sarcoplasmic reticulum. In arterial myocytes, Ca2+ sparks occur near the plasma membrane and act to deliver high (microM) local Ca2+ to plasmalemmal Ca2+-sensitive ion channels, without directly altering global cytosolic Ca2+ concentrations. The two major ion channel targets of Ca2+ sparks are Ca2+-activated chloride (Cl(Ca)) channels and large-conductance Ca2+-activated potassium (BK) channels. The activation of BK channels by Ca2+ sparks play an important role in the regulation of arterial diameter and appear to be involved in the action of a variety of vasodilators. The coupling of Ca2+ sparks to BK channels can be influenced by a number of factors including membrane potential and modulatory beta subunits of BK channels. Cl(Ca) channels, while not present in all smooth muscle, can also be activated by Ca2+ sparks in some types of smooth muscle. Ca2+ sparks can also influence the activity of Ca2+-dependent transcription factors and expression of immediate early response genes such as c-fos. In summary, Ca2+ sparks are local Ca2+ signaling events that in smooth muscle can act on plasma membrane ion channels to influence excitation-contraction coupling as well as gene expression.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Animals
  • Calcium / pharmacology
  • Calcium / physiology
  • Calcium Signaling / physiology*
  • Cell Membrane / physiology*
  • Chloride Channels / physiology
  • Gene Expression Regulation / drug effects
  • Humans
  • Ion Channels / physiology*
  • Membrane Potentials / drug effects
  • Models, Biological
  • Muscle, Smooth / metabolism
  • Muscle, Smooth / physiology*
  • Potassium Channels, Calcium-Activated / physiology
  • Ryanodine Receptor Calcium Release Channel / physiology
  • Sarcoplasmic Reticulum / physiology*
  • Signal Transduction / physiology


  • Chloride Channels
  • Ion Channels
  • Potassium Channels, Calcium-Activated
  • Ryanodine Receptor Calcium Release Channel
  • Calcium