Mechanism of positive inotropic action of the methanol extract of Fructus forsythiae in beating rabbit atria

• Published in: The FASEB journal 2007-04, Vol.21 (5), p.A584-A584
• Main Authors: Choi, Deok Ho, Kang, Dae Gill, Kim, Seung Ju, Kim, Eun Ju, Lee, Ho Sub
• Format: Article
• Language: English
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.21.5.A584-a

In the present study, the positive inotropic effects of methanol extract of Fructus forsythiae (MFF) and possible mechanisms responsible for this effect were investigated in beating rabbit atria. MFF (3 × 10−4 g/ml) significantly increased atrial stroke volume and pulse pressure without an increase in cAMP efflux in perfused beating rabbit atria. These positive inotropic effects were markedly inhibited by pre‐treatment with diltiazem or verapamil, L‐type Ca2+ channel blockers. Moreover, MFF‐induced increases in atrial stroke volume and pulse pressure were also completely inhibited by pre‐perfusion of staurosporine, a non‐specific protein kinase inhibitor. Oleanolic acid (1 × 10−4 M), a triterpenoid constituent of MFF, also increased atrial stroke volume and pulse pressure without changes in cAMP efflux. These effects were also substantially inhibited by pre‐treatment with diltiazem, verapamil, and staurosporine, respectively. Taken together, the present results suggest that MFF‐induced positive inotropic effect in beating rabbit atria might due to activity of oleanolic acid via L‐type Ca2+ channels and/or protein kinases.