Abstract
The evidence provided by a systematic in vestigation of the quantitative relationships between cocaine concentration, sodium concentration and intensity of conduction block, together with available facts in the literature has led directly to the conclusion that cocaine depresses conduction in amphibian peripheral nerves by acting as an antagonist to sodium. Furthermore, from the quantitative analysis of the interrelationship between the cocaine concentration and the applied sodium concentration the conclusion was made that the antagonism is competitive. Support for the conclusion is founded on 6 major arguments: (1) sodium has a role in nerve conduction; (2) the conduction block caused by cocaine can be alleviated simply by raising the sodium concentration applied to the nerve; (3) the antagonism between sodium and cocaine is mutual and occurs over a wide range of concentration of both participants; (4) the resultant pharmacological effect is a function of the ratio of the molar concentrations of these substances; (5) sodium-deprivation or cocaine application leads to qualitatively similar changes in the basic properties associated with nerve excitability and the conduction of impulses; (6) the cocaine molecule can fulfill to a limited extent some of the functions of the sodium ion as related to nerve excitability and conduction.
Footnotes
- Received May 31, 1960.
- © 1961, by The Williams & Wilkins Company
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