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Pflügers Archiv

, Volume 417, Issue 1, pp 117–119 | Cite as

The α1-agonist phenylephrine inhibits voltage-gated Ca2+-channels in vascular smooth muscle cells of rabbit ear artery

  • I. Declerck
  • B. Himpens
  • G. Droogmans
  • R. Casteels
Short Communication Heart, Circulation, Respiration and Blood; Environmental and Exercise Physiology

Abstract

The effects of the α1-agonist phenylephrine on the voltage-gated Ca2+-entry in vascular smooth muscle cells has been studied by measuring the agonist-induced changes of [Ca2+]i in K+-depolarized tissues. These changes have been estimated from the changes in fluorescence of the Ca2+-indicator fura-2, or have been assessed from the changes in 86Rb-efflux rate through Ca2+-activated K+-channels. Phenylephrine increases the force development in K+-depolarized tissues, but reduces [Ca2+]i and inhibits the 86Rb-efflux rate. However, in the presence of the Ca2+-entry blocker verapamil, phenylephrine increases both force development and [Ca2+]i. It is concluded that phenylephrine inhibits voltage-gated Ca2+-channels, and also induces an influx of calcium by activating a verapamil-insensitive pathway.

Key words

vascular smooth muscle phenylephrine Ca2+-channels cytosolic Ca2+ 

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Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • I. Declerck
    • 1
  • B. Himpens
    • 1
  • G. Droogmans
    • 1
  • R. Casteels
    • 1
  1. 1.Laboratorium voor FysiologieCampus Gasthuisberg, KU LeuvenLeuvenBelgium

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