Effect of dl-demethylcoclaurine on plasma cAMP in mice

The effect of dl-demethylcoclaurine-HCl (DMC) on plasma cAMP was studied in mice. The log dose-response curves of DMC and isoprenaline (ISO) and their combination with propranolol (PRO) were determined. The results showed that sc DMC 10 mg/kg caused a significant increase in plasma cAMP. Peak effect was attained at 10-15 min. The shape of the dose-response curves of DMC (1-80 mg/kg) was different from that of ISO (0.01-8 mg/kg). The maximal response in plasma cAMP induced by DMC up to 160 mg/kg was lower than that induced by ISO. The increase in plasma cAMP induced by DMC(5-160 mg/kg) was blocked by PRO. However, the block could not be overcome completely by increasing the dose of DMC to 160 mg/kg. The effect of ISO (0.02-0.1 mg/kg) in increasing plasma cAMP level was potentiated by DMC 7 mg/kg. But this effect of ISO (0.5-10 mg/kg) was antagonized by DMC 7 mg/kg. DMC had no significant influence on alpha or DA receptors. Thus, DMC seems to be a partial beta-adrenergic agonist and exhibits no noticeable effect on myocardial cAMP in rats.