REPAIR OF WOUNDED MONOLAYERS OF CULTURED VASCULAR ENDOTHELIAL-CELLS AFTER SIMULTANEOUS EXPOSURE TO LEAD AND ZINC

We investigated the interaction between lead and zinc on the repair of wounded monolayers of cultured bovine aortic endothelial cells. A hal f area of the monolayers was wounded and then incubated in the presenc e of lead (5.0 and 10 mu M) and/or zinc (10 mu M). It was morphologica lly observed that the appearance of the cells in the wounded area was strongly decreased by lead alone but considerably increased by zinc al one. The repair of wounded area after simultaneous exposure to lead an d zinc showed that lead inhibits not only spontaneous but also zinc-pr omoted repair of endothelial cell layers without a change of the leaka ge of lactate dehydrogenase. Interaction between lead and zinc on the DNA synthesis of growing endothelial cells was similar to that on the repair, suggesting that the repair reflected the proliferation. In gro wing endothelial cells, the intracellular accumulation of lead was sig nificantly increased by zinc; that of zinc was unaffected by lead; and that of metallothionein was slightly increased by zinc and lead but t he effect of zinc was suppressed in the presence of lead. Although zin c significantly decreased the intracellular accumulation of radioactiv e calcium, lead increased it in the presence or absence of zinc. It wa s therefore concluded that lead inhibits not only spontaneous but also zinc-promoted repair of the damaged endothelial cell layers through a n inhibition of the proliferation mediated by the calcium-mediated sig nalling pathways and/or a disturbance of intracellular calcium homeost asis. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.