Alterations of hepatocyte Ca2+ homeostasis by triethylated lead (Et3Pb+): are they correlated with cytotoxicity?

Reversal of ionoregulatory disruptions in occupational lead exposure by vitamin C

In order to investigate the toxic effects of lead during occupational exposure to this metal and the antidotal efficacy of ascorbic acid directed against these toxic effects, various artisans in Abeokuta, Nigeria, who have been shown to be occupationally exposed to lead were supplemented daily with 500mg ascorbic acid for 2 weeks. Ca(2+)-Mg(2+)-ATPase activity in erythrocyte membrane, as well as calcium and magnesium concentrations in plasma, erythrocytes, erythrocyte membrane and urine of the artisans were determined before and after ascorbic acid supplementation. The 2-week ascorbic acid administration resulted in the reversal of lead-induced accumulation of calcium and magnesium in the erythrocyte membranes of the artisans. Ascorbic acid also reversed lead-induced inhibition of erythrocyte membrane Ca(2+)-Mg(2+)-ATPase. Urinary excretion of calcium and magnesium was not affected by ascorbic acid. There may be some scope in introducing ascorbic acid as an intervention strategy for the prevention and therapy of lead intoxication, especially in cases where the subjects cannot be removed from the source of lead exposure.

Exocrine cell mitochondria of the rat pancreas after lead intoxication

The aim of the study was to evaluate alterations in exocrine cell mitochondria of the rat pancreas after lead acetate intoxication. The experiment used 45 rats divided into 2 experimental groups receiving lead acetate to drink, of lead concentration 50 and 500 mg/dm3 (ppm), and a control group given tap water. The animals from the experimental group were decapitated after 2, 4, 6 and 8 weeks, 5 rats from the control group after 8 weeks of the experiment. Rats from experimental groups decapitated after 8 weeks had lead administration stopped after six weeks and then, for two weeks tap water was given. Pancreatic sections were examined with biochemical methods for the activity of cytochrome oxidase and succinic dehydrogenase. Ultrastructural and morphometric examinations were also performed. It was demonstrated that: a) exocrine cell mitochondria are particularly predisposed to lead effect, b) intoxication of rats with lower lead doses (50 ppm) causes reversible adaptative or compensatory changes in these organelles, c) intoxication of rats with higher lead doses (500 ppm) induces irreversible ultrastructural alterations in numerous mitochondria, including damage to inner and to outer mitochondrial membranes, d) structural changes in the mitochondria in the course of lead intoxication are the morphological expression of the impairment of metabolic processes, associated with the inhibited activity of the respiratory enzymes: succinic dehydrogenase and cytochrome oxidase.