A STUDY OF THE ACTION OF COCAINE ON THE SPLANCHNIC AND CERVICAL SYMPATHETIC NEUROMUSCULAR MECHANISMS

¹ From the Laboratory of Physiological Chemistry and Pharmacology of the University of Chicago, Chicago

1. Cocaine intravenously administered greatly intensifies the blood pressure rise after stimulation of the peripheral end of a divided splanchnic nerve.

2. This greatly increased response is largely due to the synergism between cocaine and the epinephrine secretion subsequent to splanchnic nerve stimulation.

3. In the absence of adrenal glands cocaine still increases the effects of splanchnic stimulation.

4. The nasal plethysmograph method of Tschalussow was used for the study of cocaine effects on the cervical sympathetic neuromuscular mechanism. By this means it was found that cocaine increases the constrictor effects of electrical stimulation of the cervical sympathetic nerves.

5. Attempts to demonstrate a lowering of the threshold of excitability of sympathetic nerves, particularly those of the pupillary mechanism, were not successful.

6. Since cocaine increases the effects of epinephrine and also of electrical stimulation of such sympathetic neuromuscular mechanisms studied, these increased effects appear to be largely if not entirely due to an increased responsivity of the peripheral neuromuscular mechanism rather than direct changes in threshold of excitability of preganglionic nerve fibers.

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