Cardiac and Vascular Synergic Protective Effect of Olea europea L. Leaves and Hibiscus sabdariffa L. Flower Extracts

Table 2

Inotropic and chronotropic effects of OEE, HSE, and their mixture.

Extract	Left atrium			Right atrium
	Negative inotropy			Negative chronotropy
	Activity^a (M ± SEM)	(mg/mL)	95% conf. lim.	Activity^c (M ± SEM)	(mg/mL)	95% conf. lim.
OEE	68 ± 2.4	0.14	0.10–0.18	37 ± 2.4
HSE	76 ± 0.9	0.27	0.21–0.35	46 ± 0.7^d
Mixture	60 ± 1.4	0.16	0.12–0.20	84 ± 2.0	1.21	1.10–1.33

Decrease in developed tension on isolated guinea-pig left atrium at 1 mg/mL concentration, expressed as percent changes from the control (). The left atria were driven at 1 Hz. The 1 mg/mL concentration gave the maximum effect for most compounds. ^bCalculated from concentration-response curves (Probit analysis by Litchfield and Wilcoxon [46] with ). When the maximum effect was <50%, the EC₅₀ ino., EC₃₀ chrono., values were not calculated. ^cDecrease in atrial rate on guinea-pig spontaneously beating isolated right atrium 10 mg/mL concentration, expressed as percent changes from the control (). The 10 mg/mL concentration gave the maximum effect for most compounds. Pretreatment heart rate ranged from 165 to 190 beats/min. ^dAt 1 mg/mL concentration.