Pb2+-mediated down-regulation of dihydropyridine receptors in skeletal muscle.

This study examines the influence of chronic treatment with inorganic lead (Pb(2+)) on the presence of dihydropyridine receptors in two types of excitable cells, primary cultures of skeletal muscle and neural retina from embryonic chick. As assessed through binding of the dihydropyridine antagonist [3H] PN 200-110, treatment of skeletal muscle cultures with Pb2+ caused measurable reductions in the numbers of dihydropyridine receptors. The reductions were dose-dependent, requiring concentrations greater than 1microM, slow in onset, requiring incubation times greater than 12h, and tissue specific, being pronounced in skeletal muscle but absent from neural retina.