2,5-Di-t-butyl-1,4-benzohydroquinone (BHQ) inhibits vascular L-type Ca2+ channel via superoxide anion generation

Authors

  • Fabio Fusi,

    Corresponding author
    1. Istituto di Scienze Farmacologiche, Università degli Studi di Siena, via Piccolomini 170, 53100 Siena, Italy
      Istituto di Scienze Farmacologiche, Università degli Studi di Siena, via Piccolomini 170, 53100 Siena, Italy. E-mail: fusif@unisi.it
    Search for more papers by this author
  • Simona Saponara,

    1. Istituto di Scienze Farmacologiche, Università degli Studi di Siena, via Piccolomini 170, 53100 Siena, Italy
    Search for more papers by this author
  • Hristo Gagov,

    1. Istituto di Scienze Farmacologiche, Università degli Studi di Siena, via Piccolomini 170, 53100 Siena, Italy
    Search for more papers by this author
    • 2

      Current address: Institute of Biophysics, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 21, 1113 Sofia, Bulgaria

  • Giampietro Sgaragli

    1. Istituto di Scienze Farmacologiche, Università degli Studi di Siena, via Piccolomini 170, 53100 Siena, Italy
    Search for more papers by this author

Istituto di Scienze Farmacologiche, Università degli Studi di Siena, via Piccolomini 170, 53100 Siena, Italy. E-mail: fusif@unisi.it

Abstract

  • The aim of the present study was to investigate the effects of 2,5-di-t-butyl-1,4-benzohydroquinone (BHQ), an inhibitor of the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA), on the whole-cell voltage-dependent L-type Ca2+ current (ICa(L)) of freshly isolated smooth muscle cells from the rat tail artery using the patch-clamp technique.

  • BHQ, added to the perfusion solution, reduced ICa(L) in a concentration- (IC50=66.7 μM) and voltage-dependent manner. This inhibition was only partially reversible.

  • BHQ shifted the voltage dependence of the steady-state inactivation curve to more negative potentials by 7 mV in the mid-potential of the curve, without affecting the activation curve as well as the time course of ICa(L) inactivation.

  • Preincubation of the cells either with 10 μM cyclopiazonic acid, a SERCA inhibitor, or with 3 mM diethyldithiocarbamate, an inhibitor of intracellular superoxide dismutase (SOD), did not modify BHQ inhibition of ICa(L). On the contrary, this effect was no longer evident when SOD (250 u ml−1) was added to the perfusion medium.

  • Either in the presence or in the absence of cells, BHQ gave rise to superoxide anion formation, which was markedly inhibited by the addition of SOD.

  • These results indicate that, at micromolar concentrations, BHQ inhibits vascular ICa(L) by giving rise to the formation of superoxide anion which in turn impairs the channel function.

British Journal of Pharmacology (2001) 133, 988–996; doi:10.1038/sj.bjp.0704183

Ancillary