17β-Estradiol attenuates voltage-dependent Ca2+ currents in A7r5 vascular smooth muscle cell line

F. Zhang, J. L. Ram, P. R. Standley, J. R. Sowers

Research output: Contribution to journalArticle

182 Scopus citations

Abstract

Previous studies have shown that 17β-estradiol (β-E2) has a direct acute inhibitory effect on vascular smooth muscle (VSM) contraction. To investigate the mechanisms underlying this phenomenon, we utilized whole cell patch-clamping techniques to study effects of β-E2 on voltage-dependent Ca2+ channels in cultured VSM cells (VSMC). T- and L-type Ca2+ currents were characterized with ramp and pulse protocols in A7r5 cultured VSMC. T- type current, inactivated in < 100 ms, was reduced by Ba2+ and was comparatively little affected by isradipine. L-type current required higher voltages to activate, inactivated slowly, was greatly increased by Ba2+, and could be completely inhibited by 5 μM isradipine. β-E2 (10 μM) significantly reduced peak L-type Ba2+ current and T-type Ca2+-current within 1-2 min, whereas α-E2 (a hormonally inactive isomer of estradiol) caused significantly less reduction in both types of current. Vehicle (0.1% ethanol) had no significant effect on either current. The inhibitory effect of β-E2 on voltage-dependent Ca2+ currents may contribute to previously demonstrated β-E2 attenuation of VSM contraction.

Original languageEnglish (US)
Pages (from-to)C975-C980
JournalAmerican Journal of Physiology - Cell Physiology
Volume266
Issue number4 35-4
StatePublished - May 25 1994
Externally publishedYes

Keywords

  • L-type calcium ion channel
  • T-type calcium ion channel
  • cultured cells
  • rat
  • voltage clamp

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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