title: Effect of didrovaltrate on I-calcium current in rabbit ventricular myocytes.
abstract: OBJECTIVE
  To investigate the effect of didrovaltrate on L-type calcium current (I(Ca-L)) in rabbit ventricular myocytes.
  
  
  METHODS
  We used the whole cell patch clamp recording technique.
  
  
  RESULTS
  Didrovaltrate at concentrations of 30 microg/ L and 100 microg/L significantly decreased peak I(Ca-L) (I(Ca-Lmax)) from (6.01 +/- 0.48) pA/pF to (3.45 +/- 0.27) pA/pF and (2.16 +/- 0.19) pA/pF (42.6% and 64.1%, n=8, P< 0.01), respectively. Didrovaltrate shifted upwards the current-voltage curves of I(Ca-L) without changing their active, peak and reverse potentials. Didrovaltrate affected the steady-state inactivation of I(Ca-L). The half activation potential (V1/2) was significantly shifted from (-26 +/- 2) to (-36 +/- 3) mV (n=6, P<0.05), with a significant change in the slope factor (k) (from 8.8 +/- 0.8 to 11.1 +/- 0.9, n=6, P<0.05). Didrovaltrate did not affect the activation curve.
  
  
  CONCLUSIONS
  Didrovaltrate blocks I(Ca-L) in a concentration-dependent manner and probably inhibits I(Ca-L) in its inactive state, which may contribute to its cardiovascular effect.
authors.affiliation: Department of Cardiology, the First Affiliated Hospital of Xiamen University, Xiamen 361003, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Xie
authors.forename: Weihua
authors.initials: W
authors.lastname: Li
authors.forename: ZhengRong
authors.initials: Z
authors.lastname: Huang
authors.forename: Ziguan
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D000818:Animals; D002118:Calcium / Q000737:chemistry* / Q000378:metabolism; D002478:Cells, Cultured; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D055724:Electrophysiological Phenomena / Q000187:drug effects; D005260:Female; D006352:Heart Ventricles / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism; D039823:Iridoids / Q000494:pharmacology*; D008297:Male; D032383:Myocytes, Cardiac / Q000737:chemistry* / Q000187:drug effects* / Q000378:metabolism; D011817:Rabbits; D014632:Valerian / Q000737:chemistry*
chemical_list: D004365:Drugs, Chinese Herbal; D039823:Iridoids; C024750:didrovaltrate; D002118:Calcium