CARDIOTONIC ACTIVITY OF THE RHIZOME OF POLYGONATUM-SIBIRICUM IN RATS

The cardiotonic effect of the rhizome of Polygonatum sibivicum was inv estigated in the left atria of rats, The methanol extract of the rhizo me of Polygonatum sibivicum (OM) (1-7 mg/ml) concentration-dependently increased the developed tension of the left atrium, It also strongly inhibited cAMP phosphodiesterase, The increase cAMP level correlated t he increase in left atrial contraction, On the other hand, OM did not inhibit Na+, K+-ATPase, The cardiotonic effect of OM was strongly inhi bited by reserpine, a sympatholytic agent, Futhermore, OM-treated left atria inhibited the tension produced by propranolol, a beta adrenocep ter antagonist. These findings suggested that the cardiotonic effect i s due to stimulating beta adrenoceptors through activation of sympathe tic nerves.