Journal of
Medicinal Plants Research

  • Abbreviation: J. Med. Plants Res.
  • Language: English
  • ISSN: 1996-0875
  • DOI: 10.5897/JMPR
  • Start Year: 2007
  • Published Articles: 3834

Full Length Research Paper

Effects of astragaloside IV on L-type calcium channel currents in adult rat ventricular myocytes

Shiqi Lu1*, Guolin Chen1, Yiming Zhao1 and Wanping Sun2
1Department of Emergency, The First Affiliated Hospital of Soochow University, Suzhou 215006, China. 2Department of Pharmacology, College of Pharmaceutical Science, Soochow University, Suzhou 215123, China.
Email: [email protected]

  •  Accepted: 22 November 2011
  •  Published: 09 February 2012

Abstract

Astragaloside IV (AGS-IV), a traditional Chinese herb, has been found to have potent cardioprotective effects. However, the relevant mechanisms still remain unclear. In the present study, using standard whole-cell patch clamp recording technique, we identified a novel functional role of AGS-IV in regulating L-type calcium channel currents (L-currents) in adult rat ventricular myocytes. Our results showed that AGS-IV exerted inhibitory effects on L-currents of the single adult rat ventricular myocytes. This L-current inhibitory action of AGS-IV was concentration-dependent. The current density at +10 mV was reduced by about 48.7% after exposure of the cells to AGS-IV (1 µM), from the control value of 13.7±1.7 to 7.6±1.2 pA/pF. AGS-IV did not markedly affect the activation of L-currents but significantly shifted the inactivation curve to the left. Pretreatment of cells with H89, a protein kinase A (PKA) inhibitor, completely abolished AGS-IV-induced L-current inhibition. Similar results were obtained by another PKA inhibitor PKI 5-24. Taken together, these results suggested that AGS-IV inhibited L-currents via a PKA-dependent pathway in rat ventricular myocytes, which could contribute to its cardioprotective effects.

 

Key words: Astragaloside IV, L-type calcium channels, ventricular myocytes, patch clamp.