Evidence for a Junctional Effect of Lead on Neuromuscular Function

The Effect of Some Metal Ions on the Intradental Sensory Nerves of the Cat

“…Thus, it has been reported that Hg, Zn, Cd, and Ni ions alter the ionic currents during the action potential and block the nerve conduction in squid giant axons.5 Furthermore, Ca, Sn, and Mg ions can block the synaptic transmission between dorsal root afferents and motor neurons in the spinal cords of frogs.1 Ni ions have been found to block the conduction of action potentials in non-myelinated nerve fibers of crayfish, and Pb has been shown to inhibit nerve transmission at neuromuscular junctions. 26 The mechanism by which these metal ions reduce nerve excitability is not known. It has been suggested that this effect of heavy metals may involve a binding of metal ions to the membrane proteins4 or lipids25 or on the interface between proteins and lipids in the membrane23.…”

Environmental Toxic Neuropathies

“…High levels of inorganic lead may promote cell death by accumulation of intracellular calcium. Calcium levels are increased due to displacement of calcium ions, disruption of ion transport through calcium channels, and inhibition of calcium adenosine triphosphatase [ 7,8 ] .…”

Hyperactivity: A Lead-Induced Behavior Disorder

“…Motor activity was measured by placing a grid arrangement of 2 in square electrosensitive plates under a cage similar to those in which the animals were housed (9). Basically, the unit of activity measured was the crossing by the mouse from active to ground square.…”

“…These disorders are manifest as irritability, restlessness, and aggressiveness, but no experimental evidence has been previously advanced to support or deny the clinical experience. Although animal studies employing high levels of lead exposure have produced significant organ damage (5), encephalopathies (6, 7), and neuromuscular impairment (8,9), no behavioral dysfunction due to lead …”