1968 Volume 18 Issue 4 Pages 490-499
It is well known that all anesthetics in clinical use more or less have an action of muscle relaxation. As previously reported (1), spontaneous activities of human respiratory muscles decrease as anesthesia is deepened and finally disappear except for the activity of the diaphragm. Spontaneous activities of muscles are, however, the final reflection of various mechanisms by which each anesthetic acts on the central and peripheral nervous systems. Therefore, it is assumed that there are differences in sites and in potency of action on each synaptic level due to the specific characteristics of each anesthetic with regard to muscle relaxation. As for neuromuscular transmission, several authors reported the depressant action of anesthetic gases (2); and others (3-5) described their effects on spinal reflexes. In the above reports, however, the action of the anesthetics was focused upon only one phenomenon, namely neuromuscular transmission or spinal reflexes. In the present study on the cat the differential effects of anesthetics on neuromuscular transmission, the gamma motor system, spinal reflexes and the pathway from the central nervous system to muscle were examined simultaneously in order to detect differences in their sites and potency of action.
