ionic mechanisms of tetradrine in cultured rat aortic smooth muscle cells

Sheng Nan Wu, Tsong Long Hwang, Chung Ren Jan, Ching Jiunn Tseng

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

Abstract

The ionic mechanism of tetrandrine, an alkaloid extracted from the Chinese medicinal herb Radix stephania tetrandrae, was investigated in A7r5 vascular smooth muscle cells. The nystatin-perforated whole-cell voltage-clamp technique was performed to examine the effects of tetrandrine on ionic currents. Tetrandrine (1-100 μM) reversibly caused an inhibition of L-type voltage-dependent Ca2+ current (I(Ca,L)) in a concentration-dependent manner. Tetrandrine did not cause any change in the overall shape of the current-voltage relationship of I(Ca,L). The IC50 value of tetrandrine-induced inhibition of I(Ca,L) was 5 μM. In the presence of Bay K 8644 (3 μM) or cyclopiazonic acid (30 μM), tetrandrine still produced a significant inhibition of I(Ca,L). The inhibitory effects of tetrandrine on I(Ca,L) exhibited tonic and use-dependent characteristics. Moreover. tetrandrine (3 μM) Shifted the steady-state inactivation curve of I(Ca,L) to more negative membrane potentials by approximately - 15 mV. These results indicate that tetrandrine directly inhibits the voltage-dependent L-type Ca2+ current in vascular smooth muscle cells, which may predominantly contribute to the vasodilatory actions of tetrandrine.

Original languageEnglish
Pages (from-to)233-238
Number of pages6
JournalEuropean Journal of Pharmacology
Volume327
Issue number2-3
DOIs
Publication statusPublished - 1997 May 30

All Science Journal Classification (ASJC) codes

  • Pharmacology

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