Sweet Chestnut (Castanea sativa Mill.) Bark Extract: Cardiovascular Activity and Myocyte Protection against Oxidative Damage

Table 3

Cumulative concentration-activity curve in guinea pig heart preparations. Cardiac activity and potency of sweet chestnut bark extract.

Compound	Positive inotropy				Negative chronotropy
	Left atria		Left papillary muscle		Right atria
	Activity^a	Potency^b	Activity^c	Potency^b	Activity^d	Potency^b
Extract	45 ± 0.7	—	52 ± 1.9	0.09 (c.l. 0.07–0.13)	48 ± 1.3	—

^aIncrease in developed tension on isolated guinea pig left atrium at 1 mg/mL extract concentration, expressed as percent changes from the control (𝑛 = 5-6). Data represent mean ± S.E.M. The left atria were driven at 1 Hz. 1 mg/mL extract concentration gave the maximum effect.
^bThe EC₅₀ was expressed as mg/mL concentration that gave the 50% of the effect and was calculated from concentration-response curves (Probit analysis by Litchfield and Wilcoxon with 𝑛 = 6-7).
^cIncrease in developed tension on isolated guinea pig left papillary muscle at 1 mg/mL extract concentration, expressed as percent changes from the control (𝑛 = 5-6). The left papillary muscle was driven at 1 Hz. 1 mg/mL gave the maximum effect for extract. Data represent mean ± S.E.M.
^dDecrease in atrial rate on guinea pig spontaneously beating isolated right atrium at 1 mg/mL extract concentration, expressed as percent changes from the control (𝑛 = 7-8). Data represent mean ± S.E.M. Pretreatment heart rate ranged from 165 to 190 beats/min. 1 mg/mL gave the maximum effect for extract.