J.Jpn. Surg. Soc.. 60(14): 2076-2090, 1960

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THE STUDIES OF SPINAL CORD REFLEX IN ANESTHESIA AND ANOXIA

In order to investigate the effect of anesthetics and muscle relaxants on the reflex, knee-jerk reflex and planter reflex are examined clinically and spinal cord potentials are analysed experimentally. Tetanus rabbit were made to observe the muscle tonus through the spinal cord reflex and effect of anesthetics and muscle relaxtants on it were examined through the electromyogram.
The results obtained from the study are as follows :
(1) Spinal cord are stimulated slightly by administration of morphine. Ether and pentothal anesthesia produced marked decrease of spinal cord function in the deep anesthesia stage, and threshold of knee-jerk reflex increased. However, in the pentothal anesthesia the threshold of refiex showed no definite changes. Threshold of planter reflex increase slightly in ether and pentothal anesthesia.
Following the administration of Myanesin, the threshold of knee-jerk reflex increased for a while but it returned to the normal level quickly. Ourare injection has made remarkable rise of threshold of knee-jerk reflex.
(2) Administration of morphine produced temporary rise of the ventral cord action potentials. During ether anesthesia, action potentials rise temporarily in the II. stage anesthesia and in II. plane of III. stage it disappears.
During pentothal anesthesia action potentials did not show temporary increase and it disappear in the deep anesthesia, as well as in the ether anesthesia.
During nitrous oxide anesthesia action potential is depressed in the early III. stage, but it is considered that depression of the potential might be due not only to anesthetic process but to anoxia.
In the anoxic condition, action potential is depressed remarkably and disappear. According to anoxic complication in ether, pentothal and nitrous oxide, ventral root action potential disappear more readily.
Myanesin acts upon the interneuron nerve and the ventral action potential disappear but action time is short.
Curare acts upon the neuromuscular junction, but administration of curare produced no remarkable effect upon the ventral action potential.
(3) The author observed a spontaneous discharge and its discharge state in the stretch reflex upon the electromyogram of the stimulated muscles. Moreover, the author studied a influence of the anesthetic agents to muscle tonus.
During ether and pentothal anesthesia, muscle tonus decrease perfectly according to deep narcosis. But in the ether anesthesia muscle tonus increase temporarily at the time of introduction.
Myanesin solved the muscle tonus but the grade is not heavy and its continuation is short.
Curare solved remarkably the muscle tonus.
(Author's abstract)

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