ON THE AUTONOMIC INNERVATION OF VOLUNTARY MUSCLE AND ITS RELATION TO THE CHEMICAL REGULATION OF ITS HEAT-PRODUCTION

¹ Kuré Medical Clinic of the Tokyo Imperial University

Heat-production in the gastrocnemius is caused by impulses from the heat-regulation centre in the hypothalamus through sympathetic and parasympathetic tracts. The removal of only one of these is not sufficient to stop heat-production in muscles, but interruption of both sympathetic and parasympathetic stops chemical heat-regulation entirely. This supports the fact that there is a sympathetic and parasympathetic tonic innervation of muscle. Whether the cerebrospinal innervation plays a rôle in the heat-production we cannot yet decide. We are able to confirm the fact that the heat-production in the leg muscles is not interrupted by section of the thoracic cord, but is interrupted by section of the cervical cord. The impulses for heat-regulation pass through the sympathetic trunk; they disappear when the sympathetic is removed, after the thoracic cord is cut. Previous authors (Barcroft (22), Langley and Itagaki (23), and Nakamura) who have been unable to see changes in metabolism in muscles after cutting their nerves experimented only on animals in which there was no tendency towards an increase of heat-production. We, on the other hand, have first stimulated the heat-regulation centre and have then been able to observe that the sympathetic and parasympathetic innervations are necessary for an increase of the heat-production of muscle.

In this manner an increase of heat-production in muscle at rest is proved. Clinically it is often seen that muscle-fibrillations are promoted by adrenaline and pilocarpine and rendered less noticeable by atropine, scopolamine, and novocaine. This shows there is a certain connection between muscle-fibrillations and autonomic muscle-tonus. It is probable that in shivering from cold there are not only motor impulses causing the tremor but also an increase of autonomic impulses causing heat-production.

1. On cooling the neck of an animal and thus the blood in the carotid, heat-production is promoted in the resting gastrocnemius.

2. This heat-production in the muscle is diminished by the removal of the lumbar sympathetic trunk, or by section of the ventral roots, or by section of the dorsal roots.

3. The removal of the lumbar sympathetic trunk combined with section of the dorsal roots (of the corresponding region) causes total disappearance of the heat-production in muscle.

4. After section of the thoracic cord the heat-production does not totally disappear, but when combined with extirpation of the lumbar sympathetic trunk it disappears completely. Transaction of the cervical cord high up causes complete disappearance of heat-production in muscle.

5. The impulses which subserve heat-regulation in the muscles of the leg pass partly through the lumbar sympathetic trunk (sympathetic), and partly through the dorsal roots of the spinal cord (parasympathetic).