Chikodi Nnanyelu Anigbogu

Oxidative status in rat kidney exposed to petroleum hydrocarbons

Objective: The study investigates the possible role of oxidative stress on renal tissues in association with petroleum hydrocarbon-induced nephrotoxicity. Materials and Methods: Rats of comparable weights were randomly distributed into 10 groups: Control and groups exposed to kerosene, petrol, and diesel via inhalation, contamination by food, and contamination by water. The exposure lasted for eight weeks. Results: Exposure to petroleum hydrocarbon led to significant rise in serum urea and creatinine, and renal tissue malondialdehyde. It also caused significant reduction in urinary urea and creatinine, and reduced glutathione, superoxide dismutase, and catalase activities of renal tissue homogenate. However, serum and urine concentrations of albumin and total protein were comparable in all groups. Conclusion: Results from this study shows that exposure to petroleum hydrocarbon led to renal dysfunction via oxidative stress, increasing lipid peroxidation and reducing the antioxidant defense mechanism.

l-Arginine supplementation enhances antioxidant activity and erythrocyte integrity in sickle cell anaemia subjects

The effect of oral, low-dose l-arginine supplementation (1g/day for 6 weeks) on antioxidant activity, haematological parameters and osmotic fragility of red blood cells was investigated in sickle cell disease sufferers. Twenty eight sickle cell anaemia subjects were recruited for the study. Five millilitres of blood was withdrawn from an ante-cubital vein for the estimation of plasma arginine concentration ([R]), total antioxidant enzymes (TAE) activity, malondialdehyde concentration ([MDA]), RBC count, [Hb], PCV, MCHC, MCV, MCH, percent irreversibly sickled cells (%ISC)) and osmotic fragility of red blood cells in the subjects. l-arginine supplementation increased [R] (p<0.001), TAE activity (p<0.05) and MCV (<0.05) but reduced plasma [MDA], MCHC, MCH and %ISC (p<0.001, respectively). Δ[R] correlated positively with ΔTAE (r=0.8) and negatively with Δ[MDA] (r=-0.7) and Δ%ISC (r=-0.5). Also ΔTAE activity correlated negatively with Δ[MDA] (r=-0.7) and Δ%ISC (r=-0.6). Supplementation shifted the osmotic fragiligram to the right and reduced the concentrations of NaCl at which initial and complete lyses of erythrocytes occurred. Study showed that low-dose, oral l-arginine increased antioxidant activity, red blood cell resistance to osmotic lysis but reduced red cell density in SCD.

Exposure to petroleum hydrocarbon: implications in lung lipid peroxidation and antioxidant defense system in rat.

Objective: Various studies have implicated automobile exhausts as risk factors in cardiovascular and pulmonary diseases; however, there is little or no documentation on the role of the main source of the exhausts, petroleum hydrocarbons, on cardiopulmonary pathologies. Thus, we investigated the effect of petroleum hydrocarbons, using various petroleum products, on histomorphology of the lung and the role of lipid peroxidation in it. Materials and Methods: Control rats were not exposed to any of the petroleum products, whereas petrol-exposed, diesel-exposed, and kerosene-exposed rats were exposed to petrol, diesel, and kerosene by inhalation, respectively. Results: Exposure to petroleum hydrocarbons significantly induced lipid peroxidation with a consequent rise in malondialdehyde (MDA), and a decrease in superoxide dismutase (SOD) and catalase (CAT) activities and glutathione (GSH) level. Exposure to petroleum hydrocarbons also caused an alteration in the histomorphology of lung tissues. Conclusion: Our findings imply that exposure to petroleum hydrocarbons by inhalation is a risk factor in the pathophysiology of pulmonary dysfunction. This is associated with oxidative stress.

Relaxation response of abdominal aorta to androgens in orchidectomised Sprague–Dawley rats fed a high-salt diet

Previous studies have demonstrated the acute relaxant effects of androgens on normal arterial beds, but not on any with underlying or induced pathologies. This study investigated whether the status of the gonads affects the direct actions of androgens on isolated abdominal aorta from male Sprague-Dawley rats fed a high-salt diet. A high-salt diet reduced the relaxation response to exogenous testosterone, but not to dehydroepiandrosterone (DHEA). Orchidectomy reduced the relaxation response to both testosterone and DHEA, while testosterone replacement restored the acute vasorelaxant effect of testosterone and DHEA in both normal and high-salt diet fed rats. Gonadal status appears to be important in the acute vasorelaxant effect of androgens.

Supplementation with l-arginine stabilizes plasma arginine and nitric oxide metabolites, suppresses elevated liver enzymes and peroxidation in sickle cell anaemia

The effect of l-arginine on liver function in SCD has received little or no attention. The effect of a chronic, oral, low-dose supplementation with l-arginine (1gm/day for 6 weeks) on some liver enzymes, lipid peroxidation and nitric oxide metabolites was studied in 20 normal (non-sickle cell anaemia; NSCA) subjects and 20 sickle cell anaemia (SCA) subjects. Ten milliliters of blood was withdrawn from an ante-cubital vein for the estimation of plasma arginine concentration ([R]), alanine aminotransaminase (ALT), aspartate aminotransaminase (AST) and alkaline phosphatase (ALP), plasma total bilirubin concentration [TB], malondialdehyde concentration [MDA] and nitric oxide metabolites concentration [NOx]. Before supplementation, ALT, AST, ALP (p<0.05 respectively) and TB (p<0.001) were higher in SCA subjects than in NSCA subjects. [R] and [NOx] were higher in NSCA subjects (p<0.001 and p<0.05 respectively). Supplementation caused greater percent increases in [R], and [NOX] in SCA than in NSCA subjects (p<0.001 in each case). l-Arginine caused greater percent reductions in ALT and AST in SCA subjects but greater percent reduction in ALP in NSCA subjects (p<0.001 in each case). Changes in [MDA] and [TB] in the two groups were similar. Study shows that chronic, oral, low-dose supplementation with l-arginine improved liver function, oxidative stress, plasma arginine concentration and nitric oxide metabolites levels in NSCA and SCA subjects. Responses in SCA subjects to l-arginine were more sensitive than in NSCA subjects.

Testosterone reduces vascular relaxation by altering cyclic adenosine monophosphate pathway and potassium channel activation in male Sprague Dawley rats fed a high-salt diet

Objectives: Male gender and high-salt diet are risk factors for hypertension. The effect of chronic exposure to testosterone is an increase in vascular tone but its influence upon responses induced by other vasoactive agents is not clear. We considered the possibility of interactions between testosterone and a high-salt diet in the mechanisms that are involved in the regulation of vascular tone. Therefore, we designed experiments to assess the involvement of the cyclic adenosine monophosphate (cAMP) pathway and potassium channel activation on vascular relaxation elicited by testosterone deficiency that was induced by orchidectomy in Sprague Dawley rats on a normal or high-salt diet. Method: Weanling male rats were randomly divided into eight groups (n = 6 each) that were either orchidectomized or sham operated with or without testosterone replacement (10 mg/kg body weight of Sustanon 250 intramuscularly, Organon, Holland) and were placed on a normal or high-salt (0.3% or 8% NaCl) diet, respectively, for 6 weeks. Arterial blood pressure was determined before and weekly throughout the experiment using the tail-cuff method. Relaxation responses to forskolin and diazoxide were studied in noradrenaline (0.1 µM) precontracted aortic rings. Results: There was an increase in the systolic blood pressure of rats placed on a high-salt diet compared with control or orchidectomized rats. Orchidectomy elicited a reduction in the systolic blood pressure while testosterone replacement restored systolic blood pressure to values seen in intact rats. A high-salt diet reduced the relaxation response to forskolin and diazoxide but not in orchidectomized rats while testosterone replacement re-established the blunted relaxation response to forskolin and diazoxide. Conclusion: Inhibition of potassium channel or adenylyl cyclase activation appears to contribute to the mechanisms by which a high-salt diet increases vascular tone. These effects were counteracted by orchidectomy in male Sprague Dawley rats.

Variability in cardiovascular functions and baroflex sensitivity following inhalation of petroleum hydrocarbons

Objective: Although petroleum products are useful chemical compounds which form an integral part of our modern technology, they have been reported to cause deleterious effect on health following their inhalation. Petroleum hydrocarbons-dependent health hazards and their mechanisms have been associated with the routes of administration. This study, therefore, aimed at the isolation and chemical characterization of various petroleum products, and also investigating in rat model of Sprague dawley strain, the variability in cardiovascular functions and possible mechanism following inhalation of petroleum products. Materials and Methods: Control rats were not exposed to any form of petroleum products, while the petrol-exposed, diesel-exposed, and kerosene-exposed were exposed to petrol, diesel, and kerosene respectively. Results: When compared with the controls, all exposed groups showed a significant (P<0.05) increase in the systolic blood pressure, diastolic blood pressure, mean arterial pressure (MAP), and heart rate (HR). In comparison with the control, exposure to petroleum products also led to significant (P<0.05) increase in baroreflex sensitivity in the diesel- and kerosene-exposed rats. Baroreflex sensitivity was comparable in the control and petrol-exposed rats (P>0.05). Body weight gain was significantly (P<0.05) reduced in petroleum products exposed rats. Conclusion: These results suggest that the variability of cardiovascular functions associated with inhalation of petroleum products is in attendant to baroreflex sensitivity and resetting of arterial pressure.