Evaluation of Surinamese medicinal plants for their effects on the contractility of hypoxic guinea pig myocardial tissue

ABSTRACT

OBJECTIVE: Cardiac stunning occurs after a transient hypoxic or ischemic insult. Preparations from Anona muricata L., Bixa orelana L., Cecropia palmata Willd., Erythrina fusca Lour., Hibiscus esculentus L., Psidium guajava L., and Terminalia catappa L. were evaluated for their possible positive-inotropic effects in a laboratory model of cardiac stunning. DESIGN AND METHOD: Thus, isolated guinea pig atria perfused in oxygenated Ringer-Locke buffer, were exposed to 5-min periods of hypoxic stress and then allowed to recover for 2 x 3 min in oxygenated buffer alone or supplemented with norepinephrine (10-5 M) or a plant extract (0.001 – 1 mg/mL). Atrial contraction force (F) was measured with a force transducer and contractility was derived by calculation of dF/dt. Troponin C - a highly specific marker for heart muscle cell death - was measured in the perfusion solution in the absence or presence of the plant extracts. RESULTS: Reoxygenation led to a gradual recovery of the atria, but they remained in a state of depressed contractility for at least 4 min. However, exposure to the A. muricata, B. orellana, C. palmata, and T. catappa extracts increased the contractility by 50 to 250%. Notably, troponin C release was 3- to 6-fold higher in incubations with the two latter preparations. CONCLUSION: Preparations from A. muricata, B. orellana, C. palmata, and T. catappa may possess positive-inotropic properties that may be useful in cardiac stunning. However, those from C. palmata and T. catappa may cause myocardial damage that may limit their usefulness in this condition.