Effects of alkaloids from Corydalis decumbens on contraction and electrophysiology of cardiac myocytes

The chloroform extract of Corydalis decumbens significantly increased the beating amplitude of cultured myocardial cell sheets. Chemical analysis led to the isolation of isoquinoline and protopine alkaloids. Of these isolated alkaloids, corlumidine and (+)-adlumidine increased the beating amplitude, but (+)-egenine decreased the beating rate and beating amplitude while protopine did not show any activity. We also studied the effects of (+)-egenine and corlumidine on contractile responses and Ca²⁺ currents in single bullfrog atrial cells using the voltage-clamp method. (+)-Egenine inhibited Ca²⁺ current by 68% of the control in single cell of bullfrog atrium, while corlumidine increased Ca²⁺ current to 60% at a concentration of 0.03 mM.