Metales pesados

Lead inhibits in vitro creatine kinase and pyruvate kinase activity in brain cortex of rats.
Lepper TW, Oliveira E, Koch GD, Berlese DB, Feksa LR.
Departamento de Bioquímica, Instituto de CiênciasBásicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Lead intoxication is a serious occupational disease that constitutes a major public health problem. Lead, aheavy metal, has been used by humans for many technological purposes, which is the main reason for its widespread distribution. The toxic mechanisms of lead on the molecular machinery of living organismsinclude metal transport, energy metabolism, diverse enzymatic processes, genetic regulation, and membrane ionic channels and signaling molecules. Since lead is able to cross the blood-brain barrier itmay cause neurotoxicity. Creatine kinase and pyruvate kinase are two thiol-containing enzymes that exert a key role for cellular energy homeostasis in brain. Our main objective was to investigate thein vitro effect of lead on pyruvate kinase and creatine kinase activities of extracts and subcellular fractions from the brain cortex of rats in the presence or not of thiol-protecting substancessuch as glutathione and cysteamine. The results showed that lead inhibited the two enzyme activities and the thiol-protecting substances prevented their inhibition. These results suggest that leadinhibits creatine kinase and pyruvate kinase activity by interaction with their thiol groups. Therefore, lead may disrupt energy homeostasis and this effect may contribute to the neurological dysfunctionfound in lead exposed individuals.

Cellular mechanisms of lead neurotoxicity.

Garza A, Vega R, Soto E.
Instituto de Fisiología, Universidad Autónoma de Puebla, Pue, Mexico.
Lead (Pb2+), a heavymetal, has been used by humans for many technological purposes, which is the main reason for its present widespread distribution. Although various actions have been taken to decrease the use and...