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ON THE EFFECT OF COCAINE UPON SODIUM-DEFICIENT FROG NERVE.
1Laboratories of The Rockefeller Institute for Medical Research.
The Journal of General Physiology
|October 30, 2009
Summary
Cocaine rapidly diffuses through nerve sheaths, with its anesthetic effect enhanced in low-sodium environments. This suggests cocaine interferes with sodium
Area of Science:
- Neuroscience
- Pharmacology
- Biophysics
Background:
- Cocaine is a potent local anesthetic with a known mechanism of action involving ion channels.
- The diffusion rate of cocaine within nerve tissues and its interaction with essential ions like sodium require further elucidation.
Purpose of the Study:
- To quantify the diffusion coefficient of cocaine in the epineurium.
- To investigate the role of sodium in the anesthetic action of cocaine on nerve fibers.
- To elucidate the mechanism by which cocaine induces anesthesia in sodium-deficient conditions.
Main Methods:
- Diffusion studies were conducted to determine the coefficient of cocaine in the epineurium.
- Experiments were performed on sodium-deficient A fibers to observe the effects of cocaine.
- Electrophysiological recordings were used to assess nerve impulse conduction and anesthetic effects.
Main Results:
- The diffusion coefficient of cocaine in the epineurium was determined to be at least 0.44 x 10(-4) cm(2)/min, likely higher.
- Sodium deficiency significantly increased nerve fiber sensitivity to cocaine's anesthetic properties.
- In sodium-deficient A fibers, cocaine exhibited a biphasic action: initial impulse restoration followed by anesthesia.
Conclusions:
- Cocaine diffuses rapidly through the epineurium, with a quantifiable diffusion coefficient.
- The presence of sodium modulates cocaine's anesthetic potency, with its absence enhancing sensitivity.
- Cocaine likely exerts its anesthetic effect by interfering with sodium-dependent cellular mechanisms within nerve fibers.
