Cardiovascular effects of the aqueous extract from Caesalpinia ferrea : involvement of ATP-sensitive potassium channels

Abstract

Caesalpinia ferrea is a plant very used in the folk medicine for treatment of several diseases, such as diabetes. This study investigated the cardiovascular effects of the aqueous extract from stem bark of C. ferrea (AECF). In non-anesthetized rats, AECF (10, 20, 40, 60 and 80 mg/kg; i.v.) inducedhypotension( − 9±1; − 12±1; − 14±1; − 20±3and − 51±6%;respectively)andtachycardia(6±1;8±1;12±2;14±2and26±3%;respectively). Hypotension was not affected after atropine or L -NAME. Furthermore, AECF (40 mg/kg) induced atrioventricular block and extrasystoles, which was not affected after atropine. In intact rings of the rat mesenteric artery, AECF (0.001 – 30 mg/ml, n =6) induced relaxations of phenylephrine tonus (Emax=110±4%), which was not changed after the removal of endothelium (Emax=113±9%). In rings without endothelium pre-contracted with KCl 80 mM,phenylephrineplusKCl20 mMorphenylephrineplusglibenclamide,thecurve toAECF wassignificantlyattenuated (Emax=24±4%,70±5% and 62±7%, respectively, n =6), but was not affected in the presence of tetraethylammonium or 4-aminopyridine (Emax=125±15% and 114±7%, respectively, n =6). These results demonstrate that AECF induces hypotension associated to tachycardia; however, in dose of 40 mg/kg, AECF induces transient bradyarrhythmias. Furthermore, AECF induces vasodilatation in rat mesenteric artery which appears to be mediated by ATP-sensitive K + channel openings