Ethnopharmacological relevance: Salvia miltiorrhiza (SM, Danshen), a traditional Chinese herbal drug, has been widely used for hundreds of years to treat coronary artery disease.
Materials and methods: We studied the effects of SM on the L-type Ca(2+) current (ICa-L) with whole-cell patch-clamp technique in rat ventricular myocytes, and its influence on Ca(2+) transient and contractility using video-based edge detection and dual excitation fluorescence photomultiplier systems as well.
Results: Exposure to SM solution caused a concentration- and voltage-dependent blockade of ICa-L, and the dose of SM solution (10g/l) decreased the maximal inhibitory effect of 35.2±1.2%. However, SM solution did not significantly change the current-voltage relationship or reversal potential of ICa-L, nor did it altered the activation and inactivation gating properties of cardiac Ca(2+) channels. Meanwhile, SM decreased the amplitude of myocyte shortening and the peak value of Ca(2+) transient with a significant decrease in the time to 90% of the baseline (Tr), but the time to 10% of the peak (Tp) was not dramatically prolonged.
Conclusions: The results indicated that SM significantly inhibited L-type Ca(2+) channels, decreased [Ca(2+)]i and contractility in adult rat cardiac myocytes. These findings may be relevant to the cardioprotective efficacy of SM.
Keywords: Calcium transient; L-type calcium current; Myocyte contractility; Patch clamp; SM; SM (PubChem CID: 105117); Verapamil hydrochloride (PubChem CID: 62969).
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