Urinary excretion of 5-hydroxyindoleacetic acid, delta-aminolevulinic acid and coproporphyrin isomers in rats and men exposed to lead

Preliminary field study of hepatic porphyrin profiles of Astyanax fasciatus (Teleostei, Characiformes) to define anthropogenic pollution

The implementation of eco-toxicological assessment in South America is presently limited due to significant scientific information gaps concerning native species and their potential use as biomarkers. Recently, a common southern hemisphere fish species, Astyanax fasciatus, has been pointed out as a potential bio-indicator to anthropogenic pollution. This is a small, abundant, Neotropical characid, which is widely distributed from Central America south, to the Rio de la Plata Basin of western Uruguay. Our study found a statistically significant increase of coproporphyrin, uroporphyrin and protoporphyrin concentrations in hepatic tissues of A. fasciatus collected from a stream segment with high anthropogenic disturbance (due mainly to agricultural derivatives and motor vehicle transportation activities). Although the area studied showed differences in up and downstream limno-chemical parameters, these differences were not related to the increase of hepatic porphyrin concentrations. Based on the results of our study, we conclude that A. fasciatus is a good bio-indicator of exposure to environmental contaminants, and we propose that this abundant fish species be considered as a sentinel organism for monitoring potential disturbances to freshwater ecosystems.

Treatments with lead expedite hyperthermia-induced thromboembolism in mouse pial microvessels

Three trials were carried out to study the influence of acute and chronic treatments with lead on hyperthermia-induced thromboembolic activity in pial microvessels of adult male mice. Each trial consisted of four groups, 10 mice (approximately 33 g) per group. Three groups were injected with lead acetate dissolved in a 5% glucose solution (vehicle) at doses of 0.1, 0.5 and 1.0 mg/kg and the control group received only the vehicle. Acute treatments were by a single injection made 1 h (i.p.) in one trial and 24 h (i.p.) in another, prior to the a hyperthermic exposure at 45 degrees C. In the third trial, a single injection was given daily (s.c.) for 7 days. Mice were anesthetized by urethane (1-2 mg/kg, i.p.), the trachea was intubated, a craniotomy was performed and the mouse was placed on the microscope stage of an intravital microscopy set-up. Core body and brain surface temperatures were raised first to 37 degrees C, the animal was stabilized for 30 min then only the brain surface temperature was raised to 45 degrees C by heating the irrigating artificial cerebrospinal fluid. The hyperthermic exposure lasted for 45 min. In all trials, lead at the three doses given (low, medium and high) significantly reduced (p < 0.001) the time of initial thromboembolic activity seen. Lead exerted its influence as quickly as in 1 h, even with the low dose administered. Neither the acute nor chronic treatments affected the degree of arteriolar constriction observed or caused venular diameter change. Arteriolar patency rate at the end of experiment was higher for control than for all lead-treated groups. Data evidenced the rapidity of the adverse influence of lead on the susceptibility to thrombosis, in vivo. The enhanced initiation of thrombotic activity may be attributed to facilitated damage to the microvascular endothelium caused by lead, when challenged by hyperthermia.