Inhibition of rat platelet aggregation by a Prudhoe Bay crude oil and its aliphatic, aromatic, and heterocyclic fractions

Alterations in the concentrations of liver mitochondrial DNA, cytoplasmic total hydrocarbon and calcium in Guinea pigs after treatment with Nigerian light crude oil

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.

Comparison of the inhibitory effects of some compounds present in crude oils on rat platelet aggregation: role of intra- and extra- cellular calcium

In vitro addition of some representative aliphatic, aromatic or heterocyclic compounds present in petroleum crude oils to washed rat platelets resulted in a concentration-dependent inhibition of aggregation induced by ADP or thrombin. Increasing concentration of extracellular Ca2+ did not alter the pattern of inhibition. ADP-induced intracellular Ca2+ mobilization was unaffected by most of the compounds tested. However, Ca2+ uptake was significantly inhibited when platelets were preincubated with these agents. This suggests that some components of crude oil may inhibit platelet aggregation by bringing about alterations in the platelet plasma membrane.

The hepatotoxic potential of a Prudhoe Bay crude oil: effect on mouse liver weight and composition

The hepatotoxic properties of a Prudhoe Bay Crude Oil (PBCO) were evaluated in mice. Administration of PBCO (5.0 ml/kg body wt, daily for 2 days) to mice resulted in an increase in (i) liver wet and dry weight, (ii) hepatic total proteins, RNA, glycogen and total lipids, and (iii) individual lipids such as cholesterol, triglycerides and phospholipids. Hepatic protein biosynthesis, determined in vivo by administration of L-[14C]leucine was increased in PBCO exposed mice. The rate of 3H incorporation from 3H2O was significantly enhanced in liver fatty acids, cholesterol, triglycerides and thus ultimately in total lipids. Also, an increase in 3H incorporation was noticed in hepatic glycogen after PBCO administration. The results suggest that PBCO may induce hepatotoxicity by altering the intermediary metabolism of biochemical constituents.