title: Pharmacological evidence for calcium channel inhibition by danshen (Salvia miltiorrhiza) on rat isolated femoral artery.
abstract: This study investigated the relaxant actions of danshen (Salvia miltiorrhiza) and its lipid-soluble- and water-soluble-fractions on endothelium-denuded rat isolated femoral artery rings. Danshen, its water-soluble fraction and its lipid-soluble fraction produced relaxation of the phenylephrine-precontracted artery rings with IC50 values of 149 +/- 20 microg/mL, 160 +/- 25 microg/mL, and 23 +/- 6 microg/mL, respectively. Pretreatment of the artery rings with a non-selective potassium channel inhibitor tetraethylammonium (TEA, 10 mM) produced a significant two-fold rightward shift of the concentration-response curve to danshen and a four-fold shift to its water-soluble fraction, but had no effect on the lipid-soluble fraction. A 3.3-fold shift was produced on the concentration-response curve of danshen when the artery rings were pretreated with a mixture of 10 mM TEA, 1 mM 4-aminopyridine (K(V) blocker), 1 microM glibenclamide (K(ATP) blocker), 100 nM iberiotoxin (BK(Ca) blocker), and 100 microM barium chloride (K(IR) blocker). Involvement of Ca2+ channels was investigated in endothelium-denuded artery rings incubated with Ca2+-free buffer and primed with 1 microM phenylephrine or 60 mM KCl for 5 minutes prior to adding CaCl2 to elicit contraction. In artery rings primed with phenylephrine, pretreatment with 1 mg/mL danshen, 1 mg/mL water-soluble fraction of danshen, 0.1 mg/mL lipid-soluble fraction of danshen, and 100 nM nifedipine abrogated the CaCl2-induced contraction. On the other hand, in artery rings primed with KCl, these agents produced 40%, 25%, 53%, and 92% inhibition on the maximum contraction induced by CaCl2, respectively. Increasing the concentrations of danshen and its water-soluble fraction to 3 mg/mL, and the lipid-soluble fraction to 0.3 mg/mL further reduced the maximum contraction to 92%, 93%, and 83%, respectively. Taken together, these findings suggested the vasorelaxant actions of danshen and its fractions were produced primarily by inhibition of Ca2+ influx in the vascular smooth muscle cells and a small component was mediated by the opening of K+ channels.
authors.affiliation: From the Department of Pharmacology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China.
authors.forename: Francis Fu Yuen
authors.initials: FF
authors.lastname: Lam
authors.forename: John Hok Keung
authors.initials: JH
authors.lastname: Yeung
authors.forename: Jessica Ho Yan
authors.initials: JH
authors.lastname: Cheung
authors.forename: Penelope Mei Yu
authors.initials: PM
authors.lastname: Or
mesh_terms: D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002122:Calcium Chloride / Q000494:pharmacology; D005263:Femoral Artery / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D010936:Plant Extracts / Q000494:pharmacology*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D027561:Salvia miltiorrhiza; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects
chemical_list: D002121:Calcium Channel Blockers; D010936:Plant Extracts; D026902:Potassium Channel Blockers; D013757:Tetraethylammonium Compounds; D002122:Calcium Chloride