[Effects of isorhynchophylline on physiological characteristics of isolated guinea pig atrium].

Isorhynchophylline (Iso) inhibits the automaticity and contractile force of isolated guinea pig atrium in a concentration-dependent manner, 30 mumol/L markedly depresses adrenaline-induced automaticity, 10 mumol/L prolongs functional refractory period and decreases excitability. Furthermore, 10 mumol/L of Iso reduces the effect of ouabain on contractile force in left atrium and 0.3 mmol/L markedly inhibits the response to paired stimulation.