title: Protective effects of isorhynchophylline on cardiac arrhythmias in rats and guinea pigs.
abstract: As one important constituent extracted from a traditional Chinese medicine, Uncaria Rhynchophylla Miq Jacks, isorhynchophylline has been used to treat hypertension, epilepsy, headache, and other illnesses. Whether isorhynchophylline protects hearts against cardiac arrhythmias is still incompletely investigated. This study was therefore aimed to examine the preventive effects of isorhynchophylline on heart arrhythmias in guinea pigs and rats and then explore their electrophysiological mechanisms. In vivo, ouabain and calcium chloride were used to establish experimental arrhythmic models in guinea pigs and rats. In vitro, the whole-cell patch-lamp technique was used to study the effect of isorhynchophylline on action potential duration and calcium channels in acutely isolated guinea pig and rat cardiomyocytes. The dose of ouabain required to induce cardiac arrhythmias was much larger in guinea pigs administered with isorhynchophylline. Additionally, the onset time of cardiac arrhythmias induced by calcium chloride was prolonged, and the duration was shortened in rats pretreated with isorhynchophylline. The further study showed that isorhynchophylline could significantly decrease action potential duration and inhibit calcium currents in isolated guinea pig and rat cardiomyocytes in a dose-dependent manner. In summary, isorhynchophylline played a remarkably preventive role in cardiac arrhythmias through the inhibition of calcium currents in rats and guinea pigs.
authors.affiliation: Department of Cardiology, The First Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang Province, PR China.
authors.forename: Runtao
authors.initials: R
authors.lastname: Gan
authors.forename: Guo
authors.initials: G
authors.lastname: Dong
authors.forename: Jiangbo
authors.initials: J
authors.lastname: Yu
authors.forename: Xu
authors.initials: X
authors.lastname: Wang
authors.forename: Songbin
authors.initials: S
authors.lastname: Fu
authors.forename: Shusen
authors.initials: S
authors.lastname: Yang
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000188:drug therapy / Q000517:prevention & control*; D002118:Calcium / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects; D026121:Indole Alkaloids / Q000737:chemistry / Q000494:pharmacology*; D008516:Medicine, Chinese Traditional; D032383:Myocytes, Cardiac / Q000187:drug effects; D010042:Ouabain / Q000494:pharmacology; D000078183:Oxindoles; D051381:Rats; D017208:Rats, Wistar; D032070:Uncaria / Q000737:chemistry*
chemical_list: D015220:Calcium Channels; D026121:Indole Alkaloids; D000078183:Oxindoles; C052714:rhyncophylline; D010042:Ouabain; D002118:Calcium