EFFECTS OF MELITTEN ON ISOLATED RAT ATRIU M

AIM: To study the effects of melitten (Mel) on rat heart. METHODS: The isolated rat atria were adopted. Before and after giving Mel, the hea rt rate, contraction of atrium, post-rest contraction and staircase we re measured. RESULTS: Verapamil (Ver) 0.1 mu mol . L(-1) was found to inhibit heart rate in the right atria of rats increased by Mel 20.0 mg . L(-1). In left atria of rats, the post-rest contraction was inhibit ed and typical positive staircase was markedly attenuated by Mel 2.5 m g . L(-1). Mel possessed negative inotropic effects on both the left a nd right atria of rats. CONCLUSION: Mel possessed negative inotropic a nd positive chronotropic actions on rat heart.