Distribution of lead in the cerebellum of suckling rats following low and high dose lead exposure. A micro-PIXE analysis

Lead concentration in different compartments of the bovine eye

It is known that lead is a metabolic substitute of calcium and recently, in vitro results showed that glycosaminoglycans and proteins are capable of binding lead. Therefore, in this work, the level of lead in aqueous humor, vitreous humor, lens and sclera of bovine eyes was analyzed in order to establish a relationship between lead concentration and the contents of glycosaminoglycans, proteins, water and calcium in those structures. Lead was determined by means of atomic absorption spectrometry after acid digestion. Our results suggest a direct relationship between the contents of proteins and glycosaminoglycans, and the ability of the different eye structures to retain lead. Nevertheless, an inverse relationship between water content and lead concentration was found. No association between calcium and lead concentrations was observed.

Decreased nerve conduction velocity in optic nerve following early post-natal low-dose lead exposure

A study was made on nerve conduction velocity of the optic nerve in rats subjected to lead exposure during the first 2 weeks of post-natal life. The rats were given intraperitoneal injections with a calculated daily exposure of 7.6 micrograms (low-dose) or 15.8 micrograms (high-dose) lead g-1 body weight. Growth retardation at 30 days was seen only with the higher dose. Littermates of low-dose exposed rat were injected with vehicle only and served as controls. Lead concentrations in blood and brain were measured in rats of 20 days of age in order to ascertain that exposure was adequate in the present litters. Nerve conduction velocity of the optic nerve was examined in 14 rats of 30 days of age taken from 10 different litters. The optic nerve(s) was prepared in anaesthetized rats and placed in a flow-through incubation chamber. One stimulating and two recording tungsten electrodes were used. In all rats, three positive-negative waves, regarded as representing three functional groups of optic nerve axons, could be recorded. The last one often had a long duration and a small amplitude without distinct peaks and hence was omitted from further analysis. The mean conduction velocities for the two faster axonal groups were 16.8 and 5.4 m s-1 in control rats, 10.3 and 5.8 m s-1 in low-dose rats and 9.4 and 5.2 m s-1 in high-dose rats. The difference in conduction velocity for the fastest axons was significant for controls versus low-dose and high-dose but not for low-dose versus high-dose.(ABSTRACT TRUNCATED AT 250 WORDS)