Experimental lead encephalopathy in the suckling rat: concentration of lead in cellular fractions enriched in brain capillaries.

Five-day old rats subjected to short-term (2-day) lead exposure by gastric gavage of aqueous lead acetate at the highest non-lethal dosage (1mgPb/g body weight/day) developed a hemorrhagic encephalopathy. Capillaries and microvessels isolated from brains of these rats showed abnormal morphology consisting of an increased number of irregularly dispersed endothelial nuclei and swollen, vacuolated endothelial cells. Lead was concentrated in isolated brain capillary-microvessel fractions, as demonstrated by both atomic absorption and 210Pb tracer methods. When lead exposure was continued for 20 days (at the maximal dosage regime compatible with a 60% survival rate), the rats recovered from the initial encephalopathy and capillaries and microvessels isolated from brains of these rats appeared morphologically normal. This recovery occurred despite continued high levels of lead in the blood and in the isolated capillary-microvessel fractions, suggesting that, as capillary endothelial cells mature, they are able to adapt to the presence of large amounts of lead.