Abstract
Effects of pretreatment with gold ion or coexistence of gold and silver ions on silver-induced contracture were studied to evaluate whether different uses of gold and silver needles in patients with rheumatoid arthritis are due to different actions of these heavy metals. Simultaneous application of 20μM gold ion and 5μM silver ion prolonged the time from ion application to tension development in single fibers of frog skeletal muscle 10 fold, compared with that observed upon silver ion alone. Such fibers showed no striation disorder. When 20μM gold ion was given to fibers immediately after development of silver-induced tention, the duration of a transient component of silver-contracture was shortened and a subsequent tonic contracture no longer observed. Delayed application of gold ion to fibers at which the tonic contracture is already appeared did not inhibit silver contracture. Even after pretreatment with gold, muscle fibers deteriorated upon silver application. These findings suggest that chemical interaction of both metal ions with membrane proteins is not simple, but depends on concentrations used, application order and time of gold application after exposure of fibers to silver.
