Negative inotropic and chronotropic effects on the guinea pig atrium of extracts obtained from Averrhoa carambola L. leaves.  C.M.L. Vasconcelos, M.S. Araújo, B.A. Silva and E.A. Conde-Garcia. Brazilian Journal of Medical and Biological Research, 38 (7): 1113, 2005.

Figure 8. Concentration-response curves for the negative chronotropic effect promoted by the aqueous extract (AEx) of Averrhoa carambola in the absence (EC50 = 133 ± 58 µg/ml) or in the presence of 0.1 µM isoproterenol (ISO, EC50 = 650 ± 100 µg/ml). With ISO, the concentration-response curve was shifted to the right (*P < 0.01, paired Student t-test)) and the relative efficacy decreased from 100 to 33.4 ± 14%, P < 0.01 (27 ± 0.1ºC, N = 4 atria, 5 trials).