ABSTRACT
In the present study, the effects of aqueous-ethanolic extract from Rosa damascene on heart rate and contractility were examined. Isolated guinea-pig hearts were perfused through aorta in a Langendorff mode. Heart rate [HR] and contractility were determined in the presence of four concentrations of the extract [0.1, 0.2, 0.4 and 1.0 mg%] and isoprenaline [1, 10, 100 nM and 1 micro M] in comparison with baseline values in the presence and absence of propranolol [n= 10 for each group]. Both isoprenaline and the extract caused increase in heart rate and contractility [P< 0.05 to P<0.001]. The percent increased in HR due to the final concentration of isoprenaline in the absence of propranolol was significantly greater than that of the extract [P< 0.01]. Propranolol caused significant reduction in both HR and contractility [P<0.05 for both] but this effect was significantly reversed by isoprenaline and the extract [P<0.05 to P<0.001]. The percent increased in heart contractility due to the final concentration of the extract in the absence and presence of propranolol was significantly greater than that of isoprenaline [P< 0.05 for both cases]. There was significant correlation between both HR and heart contractility with concentration of isoprenaline and the extract [P<0.05 to P<0.001]. In conclusion this study showed a relatively potent inotropic and chornotropic effect for Rosa damascene on isolated guinea-pig heart