Cardiac evaluation after experimental intoxication by Amorimia rigida (Malpighiaceae) extracts in rabbits

Abstract

Clinical and laboratory changes were evaluated in rabbits after intoxication by Amorimia rigida, a plant that causes sudden death. Nine New Zealand male rabbits, averaging 3.54 kg, were categorized into three groups (n = 3) and received, for eight consecutive days, the equivalent of 30 g/kg dry matter of A. rigida water-soluble (SG) and water-insoluble (IG) extracts via nasoesophageal route. The control group received water. There were no alterations in creatine kinase enzyme (CK), CK myocardial fraction (CKMB) or troponine I (cTnI). None of the animals had clinical or electrocardiographic (conventional and Holter) alterations. There were progressive decreases in the left ventricular ejection fraction and systolic fractional shortening. Doppler echocardiography alterations suggested a systolic dysfunction in the SG and IG groups and diastolic dysfunction in IG group. It was concluded that the soluble and insoluble extracts of A. rigida cause deficit of cardiac function.Key words: toxic plant, Amorimia rigida, cardiac muscle profile, electrocardiography, echocardiography, rabbit. Original PaPer The Journal of Venomous Animals and Toxins including Tropical Diseases ISSN 1678-9199 | 2012 | volume 18 | issue 3 | pages 295-305 INTRODUCTIONThe genus Amorimia (Malpighiaceae) contains one of the 10 most important toxic plants in South America (1), best known of which is Amorimia rigida (Mascagnia rigida), well distributed in Minas Gerais state (Brazil), mainly in the northern and northeastern regions, where it is popularly known as "salsa-rosa" or "suma-roxa". It belongs to a group that causes acute intoxication that may provoke death preceded or not by a short period of clinical signs (2).After A. rigida intake, animals may show apathy, anorexia, rigid walking, prolonged recumbence, muscle tremors and death, among other clinical signs. Significant alterations have not been found at necropsy of animals intoxicated by A. rigida. Multifocal infiltrate of lymphocytes in the myocardium associated with edema and congestion of myocytes was found in the histological exams (3).Studies are necessary to elucidate which physiopathological mechanisms are involved in A. rigida intoxication that leads to sudden death. In spite of the existence of some reports of mortality in the absence of cardiac lesions, it is suggested that the main action of this plant in the heart may be due to its phytochemical characteristics that might affect cardiac function within a period insufficient to produce alterations detectable by optical microscopy (4).To the best of our knowledge, no previous study has concurrently evaluated continuous electrocardiography (Holter), Doppler echocardiography and the cardiac muscle biochemical profile in animals after the intake of A. rigida. Thus, the present work aimed to ascertain the influence of this plant on the cardiac system using the rabbit as the experimental model. MATERIALS AND METHODS Animal AssaysNine six-month-old white New Zealand male rabbits weighing an average of 3.54 kg were used. Firstl...