CHRONIC TRIETHYLTIN EXPOSURE REDUCES THE RESTING MEMBRANE-POTENTIAL OF RAT SOLEUS MUSCLE

  • 1 January 1982
    • journal article
    • research article
    • Vol. 4  (2) , 255-257
Abstract
Muscle weakness is a prominent component of the toxic syndrome which results from prolonged exposure to triethyltin (TET). The etiology of this phenomenon includes an alteration of acetylcholine (ACh) release from motoneurons, but there are also indications that TET causes a primary myopathy. Chronic exposure of rats of TET bromide (30 mg/l drinking water) caused a time-dependent reduction of resting membrane potentials (RMP) recorded in situ from soleus muscle fibers. The RMP of TET-exposed rats were significantly lower than those of controls (5.4 mV) after 4 days and were further reduced by continuous TET exposure to 11.2 mV less than control on the 28th day. Three weeks after rats were withdrawn from TET, RMP were restored to control values. TET had no effect on the frequency, amplitude or incidence of occurrence of miniature endplate potentials. Spontaneous ACh release and its action on the postsynaptic membrane were not affected by TET, which suggested that TET reduced RMP through an effect on muscle fibers unrelated to denervation. TET reduced RMP by inhibiting the bioenergetic capacity of the muscle; this myogenic toxicity was a significant factor in the development of muscle weakness following exposure.