title: The interactions of paeoniflorin and veratrine on isolated rat atria.
abstract: In this study, we attempted to identify the interactions and mechanisms between veratrine and paeoniflorin on isolated rat atria. Paeoniflorin alone showed no effect on the rat atria. Veratrine increased the atrial contraction and induced arrhythmia at 1 x 10(-5) g/ml. Veratrine could directly induce contraction and elicit tetanic contraction at 1 x 10(-4) g/ml in the left atria with or without electric stimulation. Paeoniflorin (4.8 x 10(-6) to 4.8 x 10(-3) g/ml), verapamil (2.2 x 10(-6) g/ml), tetrodotoxin (TTX) (3.2 x 10(-8) g/ml) and quinidine (7.5 x 10(-6) g/ml) inhibited the increase of contraction and delayed the onset of contraction induced by veratrine (1 x 10(-5) g/ml). The inhibitory effect of paeoniflorin combined with verapamil on the contraction induced by veratrine was more potent than that of paeoniflorin or verapamil alone. However, the inhibitory effect of paeoniflorin was not potentiated by TTX or quinidine. From the above results, the contraction evoked by veratrine in the rat atria may be concluded to be caused by the stimulation of Na(+)- and Ca(2+)-ion channels. The inhibition of paeoniflorin on the contraction induced by veratrine may primarily be related to the blockade of Ca2+ channels.
authors.affiliation: Department of Pharmacology, China Medical College, Taichung, Taiwan, ROC. hytsai@cmce.cmc.edu.tw
authors.forename: H Y
authors.initials: HY
authors.lastname: Tsai
authors.forename: Y T
authors.initials: YT
authors.lastname: Lin
authors.forename: Y F
authors.initials: YF
authors.lastname: Chen
authors.forename: C F
authors.initials: CF
authors.lastname: Chen
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000188:drug therapy*; D001565:Benzoates; D001952:Bridged-Ring Compounds; D015220:Calcium Channels / Q000187:drug effects; D005960:Glucosides / Q000378:metabolism / Q000494:pharmacology* / Q000627:therapeutic use; D006325:Heart Atria / Q000187:drug effects / Q000378:metabolism; D041743:Herb-Drug Interactions; D066298:In Vitro Techniques; D008297:Male; D039821:Monoterpenes; D009200:Myocardial Contraction / Q000187:drug effects*; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D010946:Plants, Medicinal / Q000378:metabolism / Q000627:therapeutic use; D051381:Rats; D017208:Rats, Wistar; D015222:Sodium Channels / Q000187:drug effects; D013997:Time Factors; D014702:Veratrine / Q000378:metabolism / Q000633:toxicity*; D006027:Glycosides
chemical_list: D001565:Benzoates; D001952:Bridged-Ring Compounds; D015220:Calcium Channels; D005960:Glucosides; D039821:Monoterpenes; D010936:Plant Extracts; D015222:Sodium Channels; D014702:Veratrine; C015423:peoniflorin; D006027:Glycosides