Methylmercury induced neuromuscular dysfunction in the rat.
Rats were exposed to 20 mg/kg methylmercury for 10-18 days. The isolated phrenic nerve-hemidiaphragms from these animals demonstrated a reduced capability to maintain contraction amplitude when stimulated at a frequency of 10/sec. The addition of neostigmine directly to the organ bath produced a contraction enhancement significantly lower than normal. In a different series of isolated preparations, it was demonstrated that methylmercury at a final bath concentration of 2 x 10(-5) M could inhibit contractions completely with only a small degree of recovery. The muscles still responded to direct stimulation and nerve action potentials appeared unchanged. These observations may account for the muscular weakness in methylmercury intoxicated rats.
Von Burg
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Department of Pharmacology and Toxicology, University of Rochester, School of Medicine and Dentistry, Rochester, N.Y. U.S.A.
Landry
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