Abstract
Glazer 1 has shown that intravenous injection of sodium cyanide increases the reflex response of the anterior tibialis muscle to electrical stimulation. The purpose of this group of experiments was to make a similar comparison of the effects of intravenous injections of sodium sulphide on reflex response and respiratory movements.
The anterior tibialis muscle was isolated, its insertion severed and secured by a thread to a writing lever. A large copper indifferent electrode was fastened to the shaven side of the neck, and a sharp point electrode thrust into the plantar surface of the foot. The trachea was connected to a rebreathing tank for a recording respiration.
An increase in reflex response always followed an injection if it were large enough. Forty-four injections of varying amounts were given to 17 dogs. Two injections caused an increase before hyperp-nea had begun, 8 increases began with hyperpnea, and ended with it, 10 began during hyperpnea and lasted into apnea, 12 began during hyperpnea and lasted through apnea and 4 began after hyperpnea and lasted through apnea. Eighteen injections were followed by no apnea. Fatal injections always caused a pronounced increase in reflex response.
Since hyperpnea leads to increased elimination of carbon dioxide it was essential to determine whether the increased reflex response was of this origin. This was accomplished by repeating the above experiments during constant artificial ventilation after the establishment of pneumothorax. The results of 21 injections on 10 animals were comparable to those obtained in the intact animal with ventilation under normal control.
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