Abstract
The alteration of cellular calcium sequestration has been postulated to be a primary mechanism in the initiation of irreversible cell damage. Crude oil has been shown to cause concentration- dependent inhibition of calcium influx and mitochondrial swelling which may relate to its toxicity. Nigerian 'Bonny' Light Crude Oil (BLCO) is produced in the Niger-Delta region of Nigeria where oil spills are frequent and can endanger human-health, yet BLCO has not been studied in this regard. We have studied the effects of two doses of BLCO on mitochondrial DNA (mt.DNA), cytoplasmic total hydrocarbon concentrations (cyt.THC) and cytoplasmic Ca2+ (cyt.Ca2+) concentrations in livers of adult male guinea pigs exposed by intraperitoneal injection. The results showed that at 2.5 and 5.0 (ml/kg bw), BLCO caused dose-related increases in mt.DNA concentrations (128% and 485%) respectively over the controls, and cyt.THC (47.5% and 100%) respectively; while it caused near-100% decrease in cyt.Ca2+ concentrations (94% and 96.8%) respectively lower than the controls. These results suggest that BLCO caused the increased availability of crude oil hydrocarbons in the liver cells, and subsequent induction of unscheduled mt.DNA synthesis, and alteration of mitochondrial/endoplasmic reticulum Ca2+ sequestration or ca2+ - concentration gradient, leading to the inhibition of Ca2+ influx into the cytosol. These events may explain the probable hepatotoxicity of BLCO.
Highlights
Crude oils are complex mixtures of a vast number of individual chemical compounds, the bulk of which are hydrocarbons [1]
We reported that the concentration of crude oil total hydrocarbons (COTH) increased in a dose-related manner in the lungs more than in the liver at 2.5 ml/kg bw, but was higher in the liver than the lungs at 5.0 ml/kg bw when Bonny’ light crude oil (BLCO) was administered to adult male guinea pigs by intraperitoneal injection (i.p) and that the specific activity of the mitochondrial ‘marker’ enzyme, succimic dehydrogenase increased markedly at 5.0 ml/kg bw over the untreated controls [5]
The results from this study show that BLCO, when given to adult male guinea-pigs by intraperitoneal injection at two varying doses of 2.5 ml/kg bw and 5.0 ml/kg bw, caused large dose-related increases in the concentrations of liver mt.DNA and cyt.THC; while it caused large, but dose-independent decreases in cyt.Ca2+ concentrations in the livers of treated, when compared to untreated control animals
Summary
Crude oils are complex mixtures of a vast number of individual chemical compounds, the bulk of which are hydrocarbons [1]. Nigerian ‘light’ crude oil, commonly referred to as ‘Bonny’ light crude oil (BLCO) has a higher content of aliphatic hydrocarbon (light fraction) than aromatic hydrocarbon (heavy fraction) in an 80:20 ratio, it is referred to as ‘light’ crude oil (Nigerian National Petroleum Corporation – NNPC, personal communication). It is Nigeria’s major foreign exchange earner and is produced exclusively in the Niger-Delta region of Nigeria where oil spillages occur frequently which endanger human-health and the eco-system. 15-fold increase in dermal benzo(a)pyrene 3-hydroxylase activity after the application of Kuwaiti crude oil (0 –200 μg) to the skin of male Sprague-Dawley rats has been reported [2]; while the oral administration with Prudhoe Bay crude oil to SpragueDawley rats 24h after treatment showed the inhibition of platelet aggregation by aliphatic, heterocylic and aromatic fractions of the crude oil [3]
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