Cadmium reduces extraocular muscle contractility in vitro and in vivo

Cadmium, a blocker of calcium channels in various excitable cells, reduces the contractility of extraocular muscles. When applied to rat extraocular muscles in vitro, it reduces the sustained or tonic tension generated by the tonic multiply innervated fibers of the global layer of the muscles. When injected in vivo into rabbit extraocular muscles, it produces a temporary paralysis of the muscles and a deviation of the eye position. These effects are presumed to involve a blockade of the calcium channels of the muscle fibers and of the neuromuscular junctions. It is proposed that, on the basis of these effects, a non-surgical treatment of strabismus could be developed.