Changes in Cardiovascular Functions Haematologic and Metabolic Enzyme Activities in Sprague Dawley Rats Exposed to Petroleum Products.

Increased blood pressure has been associated with exposure to petroleum products by inhalation or administration of contaminated water. The mechanism of action has however not been elucidated. This study was undertaken to investigate the effect of petroleum products on cardiovascular functions using three different routes of administration and the possible involvement of oxidative stress in the mechanism of action. Sprague Dawley rats were divided into four main groups; control, diesel (automotive gas oil), kerosene (dual purpose kerosene) and petrol (premium motor spirit). Each of the groups except control was subdivided into three; ingestion, inhalation and water contaminated groups; with 10 rats in each group and sub-group. The control was not exposed to any treatment. The diesel, kerosene and petrol sub-groups, were exposed to their corresponding contaminants via ingestion, inhalation and water contamination respectively. Each administration and exposure lasted eight weeks. The results showed that blood pressure and heart rate were significantly increased (p<0.05) in the treated groups when compared with control. However, there was insignificant reduced blood pressure in petrol ingestion group. The significant increase in the blood pressure and heart rate persisted one week after stoppage of exposure in all the groups; suggesting that exposure to petroleum products could cause hypertension; the effect could be as a result of the ability of petroleum products to cause sensitization of the vascular smooth muscle to catecholamines, elicited by impaired endothelium-dependent and -independent vasomotor function. Baroreflex response was significantly (p<0.05) increased in diesel and kerosene groups compared with control, however the increase in the petrol was only significant for a while and returned to the control level by 25 seconds. This suggests that with exposure to petrol the baroreceptors still reset the blood pressure to a new higher than normal value as though normal. The activities of baroreceptors have been altered by diesel and kerosene such that they could no longer reset the arterial blood pressure. Exposure to diesel was most deleterious in all except in the inhalation group. There was reduced body weight gain (p<0.05) in all exposed rats, which was most severe in the diesel group, when compared with control as well as kerosene and petrol groups. Exposure to petroleum products dissolved fat and lipid in the body causing degeneration of fat store. The reduced weight gain might also be associated with decreased food intake seen in the study especially the diesel group. Anaemia was implicated as there were significant (p<0.05) reductions in RBC, PCV, and Hb. Platelets and lymphocyte reduced significantly in diesel and petrol groups but not significant in kerosene groups. A significant increase in WBC was recorded in diesel, kerosene and petrol groups. Liver damage as a result of increased reactive oxygen species was more severe in the diesel ingestion group as Alanine amino transferase (ALT), Aspartate amino transferase (AST) and Alkaline phosphatase (ALP) increased significantly p<0.05) in all the groups. The results also showed significant increase in lipid peroxidation, as concentration of MDA increased significantly (p<0.01) in all the treated groups. Catalase (CAT), Glutathione reductase (GSH) and superoxide dismutase (SOD) activities were (p<0.05) reduced significantly in serum and tissue homogenate at varying proportions in the different groups. In the urine samples there was significant reduction in creatinine and urea value compared with control, while creatinine and urea in serum increased significantly suggesting renal function impairment. In conclusion, exposure to petroleum products resulted in increased blood pressure and heart rate; the baroreceptors were impaired by diesel and kerosene; caused anaemia, reduced platelets and lymphocytes and caused renal dysfunction. The severity of the effects was most severe in the diesel groups. This study suggests that afore-mentioned observations are partly caused by oxidative stress by altering the levels of CAT, GSH, SOD and MDA.
A Thesis Submitted to the School of Postgraduate Studies, University of Lagos.
Cardiovascular , Haematologic Enzyme , Metabolic Enzyme , Blood Pressure , Research Subject Categories::MEDICINE::Physiology and pharmacology::Physiology
Azeez, O.M (2014), Changes in Cardiovascular Functions Haematologic and Metabolic Enzyme Activities in Sprague Dawley Rats Exposed to Petroleum Products. A Thesis Submitted to University of Lagos School of Postgraduate Studies Phd Thesis and Dissertation, 227pp.