Local Tetanism, a Tool for Understanding the Stretch Reflex

Abstract

Publisher Summary This chapter presents an experiment to study stretch reflex using local tetanism. Tetanus toxin is injected into the gastrocnemius muscle of the left hindleg of the cat. Tetanus toxin is transported in the motor fibers and reaches the spinal cord within 24 hr. After the appearance of the first symptom, a slight hobbling, the intoxication develops rapidly to a rigid extension of the whole hindleg of the injected side. At a very low dose, five minimum lethal doses/kg, the tetanic contraction could be observed only in the gastrocnemius muscle. Most acute experiments are performed at that stage of intoxication, when the symptoms are most highly developed. Cats are anesthetized with a mixture of urethane and chloralose. For the reflex tension experiments, the care was taken that the critical level of anesthesia is controlled in order to maintain a good stretch reflex. In the control experiments on non-intoxicated animals, the decerebration is performed under ether anesthesia that is ceased thereafter.