EDRF-release and Ca+(+)-channel blockade by magnolol, an antiplatelet agent isolated from Chinese herb Magnolia officinalis, in rat thoracic aorta

Life Sci. 1990;47(13):1153-61. doi: 10.1016/0024-3205(90)90176-r.


Magnolol is an antiplatelet agent isolated from Chinese herb Magnolia officinalis. It inhibited norepinephrine (NE, 3 microM)-induced phasic and tonic contractions in rat thoracic aorta. At the plateau of the NE-induced tonic contraction, addition of magnolol caused two phases (fast and slow) of relaxation. These two relaxations were concentration-dependent (10-100 micrograms/ml), and were not inhibited by indomethacin (20 microM). The fast relaxation was completely antagonized by hemoglobin (10 microM) and methylene blue (50 microM), and disappeared in de-endothelialized aorta while the slow relaxation was not affected by the above treatments. Magnolol also inhibited high potassium (60 mM)-induced, calcium-dependent (0.03 to 3 mM) contraction of rat aorta in a concentration-dependent manner. 45Ca(+)+ influx induced by high potassium or NE was markedly inhibited by magnolol. Cyclic GMP, but not PGI2, was increased by magnolol in intact, but not in de-endothelialized aorta. It is concluded that magnolol relaxed vascular smooth muscle by releasing endothelium-derived relaxing factor (EDRF) and by inhibiting calcium influx through voltage-gated calcium channels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aorta / drug effects
  • Biphenyl Compounds / isolation & purification
  • Biphenyl Compounds / pharmacology*
  • Calcium / metabolism
  • Calcium Channels / drug effects*
  • Cyclic GMP / metabolism
  • Drugs, Chinese Herbal / isolation & purification
  • Drugs, Chinese Herbal / pharmacology*
  • Endothelium, Vascular / drug effects
  • Epoprostenol / metabolism
  • Female
  • Hemoglobins / pharmacology
  • In Vitro Techniques
  • Lignans*
  • Male
  • Methylene Blue / pharmacology
  • Nitric Oxide / metabolism*
  • Norepinephrine / pharmacology
  • Platelet Aggregation Inhibitors / isolation & purification
  • Platelet Aggregation Inhibitors / pharmacology*
  • Rats
  • Rats, Inbred Strains
  • Vasoconstriction / drug effects*


  • Biphenyl Compounds
  • Calcium Channels
  • Drugs, Chinese Herbal
  • Hemoglobins
  • Lignans
  • Platelet Aggregation Inhibitors
  • magnolol
  • Nitric Oxide
  • Epoprostenol
  • Cyclic GMP
  • Calcium
  • Methylene Blue
  • Norepinephrine