Ranunculus muricatus Linn. (RML) have been traditionally used for the treatment of various cardiovascular disorders. The aim of present study was to evaluate their cardiovascular effects in isolated perfused rabbit heart. The methanolic extract of RML was prepared by cold maceration process. The methanolic extract of RML (1 ng to 10 mg) was used to determine the percentage change in force of contraction (FC), heart rate (HR) and perfusion pressure (PP) by using Langendorff's Perfused Heart Apparatus. The PP, FC and HR of isolated rabbit heart were measured by power lab data acquisition system. Moreover, phytochemical analysis and acute toxicity study were also performed. The methanolic extract at the doses from I ng to 10 mg exhibited a significant increase in perfusion pressure and force of contraction. Moreover, the crude extract of RML revealed a significant increase in heart rate at doses from 1 ng to μg. The maximum rise in all the thee parameters was observed at 1 μg and 1 ng, respectively In another study, the melhanoliC extract was tested in the presence of propranolol and verapamil on isolated perfused rabbit heart. The study shown that the increase in HR and FC produced by the plant extracts was significantly reduced in the presence of propranolol whereas PP remained significantly raised even in the presence of propranolol. However, in the presence of verapamil, this increased PP was significantly reversed to a decrease while a significant positive inotropic and chronotropic effects were observed. It is concluded that the cardiotonic activity of methanolic extract of RML might be due certain cardio active chemical compounds. Further studies are needed to isolate these pharmacologically active phytochemical constituents and elucidate their exact mechanism of action.
