Calcium Release Events in Excitation–Contraction Coupling in Smooth Muscle

  1. Derek J. Chadwick Organizer and
  2. Jamie A. Goode
  1. T. B. Bolton,
  2. D. V. Gordienko,
  3. V. Pucovský,
  4. S. Parsons and
  5. O. Povstyan

Published Online: 7 OCT 2008

DOI: 10.1002/0470853050.ch12

Role Of The Sarcoplasmic Reticulum In Smooth Muscle: Novartis Foundation Symposium 246

Role Of The Sarcoplasmic Reticulum In Smooth Muscle: Novartis Foundation Symposium 246

How to Cite

Bolton, T. B., Gordienko, D. V., Pucovský, V., Parsons, S. and Povstyan, O. (2002) Calcium Release Events in Excitation–Contraction Coupling in Smooth Muscle, in Role Of The Sarcoplasmic Reticulum In Smooth Muscle: Novartis Foundation Symposium 246 (eds D. J. Chadwick and J. A. Goode), John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/0470853050.ch12

Author Information

  1. Department of Pharmacology & Clinical Pharmacology, St George's Hospital Medical School, Cranmer Terrace, London SW170RE, UK

Publication History

  1. Published Online: 7 OCT 2008
  2. Published Print: 15 JUN 2002

Book Series:

  1. Novartis Foundation Symposia

Book Series Editors:

  1. Novartis Foundation

ISBN Information

Print ISBN: 9780470844793

Online ISBN: 9780470853054

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Summary

Although smooth muscle cells are not organized in sarcomeres, as are striated muscles, nevertheless Ca2+ for contraction is released from the sarcoplasmic reticulum (SR) at certain preferred sites. These sites commonly discharge packets of Ca2+ spontaneously and have been called frequent discharge sites (FDSs). Each spontaneous release of a Ca2+ packet usually leads to a burst of openings of Ca2+-activated K+ channels in the cell membrane which produces a spontaneous transient outward current (STOC) in smooth muscle cells under voltage clamp. When fluorescent Ca2+ indicators such as Fluo-3 became available, the spontaneous transient increases in [Ca2+]i produced by Ca2+ packets released from the SR were also detected in cardiac muscle as flashes of fluorescence or ‘sparks’. Sparks in smooth muscle consist of smaller Ca2+ packets that can give rise to ‘microsparks’. In some smooth muscles which have Ca2+-activated Cl channels, STICs (spontaneous transient inward currents) are also found to be associated with sparks. FDSs have been found to be important initiating sites for a Ca2+ wave in response to an action potential or in response to receptor activation and possibly other stimuli, such as stretch. In both cases Ca2+ -induced Ca2+ release seems to be crucially involved.