The ameliorative effects of Moringa oleifera leaf extract on cardiovascular functions and osmotic fragility of wistar rats exposed to petrol vapour OM Azeez*, SA Adah, FH Olaifa, A Basiru & R AbdulbakiUniversity of Ilorin, Ilorin, Nigeria *Correspondence: Tel.: +2348033858362; E-mail: misibisol@yahoo.com Abstract The present study was aimed at evaluating the ameliorating effects of Moringa oleifera extract compared to captopril and candesartan cilexetil on cardiovascular functions and osmotic fragility of rats exposed to petrol vapour. Twenty five adult male Wistar rats (130g-200g) were randomly grouped to five with five rats in a group. Group 1 (control) was not exposed to petrol fume. Groups 2 (petrol only), was exposed to petrol fume only. Groups 3, 4 and 5 were pretreated with Moringa oleifera extract (40mg/kg), captopril (25 mg/kg) and candesartan (16mg/kg), respectively before exposure to petrol vapour, 10 minutes every day for eight weeks. All groups were given feed and water ad-libitum. Petrol vapour was generated by using human compressor nebulizer adopted for rats and connected to fume chamber where the rats were kept. The pretreatment were administered by oral cannula. At the end of the exposure, 0.2ml of blood samples obtained from individual rat in each group were suspended in separate sets of Phosphate buffer saline (PBS) solution of decreasing concentrations. Erythrocyte osmotic fragility (EOF) was determined by spectrophotometer. Electrocardiography was done using EDAN 10. There was significant increase (p<0.05) in EOF of the rats exposed to petrol vapour only. However, Moringa oleifera, captopril and candesartan cilexetil significantly ameliorated this effect. There was no significant difference in the amelioration of Moringa oleifera and candesartan cilexetil. There was absence of p-wave and significant increase in heart rate observed in the electrocardiogram of petrol only group, this was significantly restored in the Moringa oleifera, captopril and the candesartan cilexetil group. The results showed that exposure to petrol vapour elevated EOF, resulted in atria arrhythmia and increased heart rate. These effects were ameliorated by pretreatment with Moringa oleifera, captopril and candesartan cilexetil. The amelioration in Moringa oleifera was comparable with that of candesartan cilexetil suggesting that Moringa oleifera may be an Angiotensin II receptor blocker.