Optimization on preparation of Ginkgo biloba extract-β-cyclodextrin inclusion complex by central composite design and response surface Effect of GBE50 on action potentials in normal and simulated ischemic guinea pig papillary muscles Effects of GBE50 on physiological characteristics and intracellular free calcium of myocardium Optimization on preparation of Ginkgo biloba extract-β-cyclodextrin inclusion complex by central composite design and response surface Effect of GBE50 on experimental arrhythmias