Muscle weakness is a side effect of the chronic administration of emetine [(-)emetine] in the treatment of amoebiasis. The precise nature of the weakness is still controversial. In this study we were interested in whether or not emetine can alter the electrical behavior of muscle fibers when applied to the nerve at some distance from the muscle. To test this idea, silastic cuffs containing 0.1 to 0.2% emetine were placed on the peroneal nerve of adult rats and the electrical properties of the extensor digitorum longus (EDL) muscle fibers were monitored in vitro at 4 to 40 days after application of the cuff. Action potential generation was affected by emetine treatment: the rheobasic current was significantly lowered (from a control value of 78 to 40 nA), and a small increase in current in the treated fibers produced seven or more action potentials. In the emetine-treated fibers, mean chloride conductance G(Cl) decreased from a control value of 3737 to 2453 ?S/cm2 while mean potassium conductance G(K) showed an insignificant increase from 304 to 408 ?S/cm2. We conclude that emetine interferes with specific materials involved in the maintenance of the high resting G(CI) of mammalian skeletal muscle fibers.
ELECTRICAL PROPERTIES OF RAT EXTENSOR DIGITORUM LONGUS MUSCLE AFTER CHRONIC APPLICATION OF EMETINE TO THE MOTOR NERVE.
CONTE, Diana;
1982-01-01
Abstract
Muscle weakness is a side effect of the chronic administration of emetine [(-)emetine] in the treatment of amoebiasis. The precise nature of the weakness is still controversial. In this study we were interested in whether or not emetine can alter the electrical behavior of muscle fibers when applied to the nerve at some distance from the muscle. To test this idea, silastic cuffs containing 0.1 to 0.2% emetine were placed on the peroneal nerve of adult rats and the electrical properties of the extensor digitorum longus (EDL) muscle fibers were monitored in vitro at 4 to 40 days after application of the cuff. Action potential generation was affected by emetine treatment: the rheobasic current was significantly lowered (from a control value of 78 to 40 nA), and a small increase in current in the treated fibers produced seven or more action potentials. In the emetine-treated fibers, mean chloride conductance G(Cl) decreased from a control value of 3737 to 2453 ?S/cm2 while mean potassium conductance G(K) showed an insignificant increase from 304 to 408 ?S/cm2. We conclude that emetine interferes with specific materials involved in the maintenance of the high resting G(CI) of mammalian skeletal muscle fibers.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
