THE SLOW POTENTIAL OBSERVED IN THE DORSAL COLUMN-ROOT PREPARATION

PART II. THE CONCENTRATION EFFECTS OF DRUGS ON THE SLOW POTENTIAL

Abstract

1. The ACh mechanism was examined in the dorsal column-root preparation.
2. ACh and many Anti-ChEs decreased the magnitude of the slow potentialwhen their concentrations were high, while they increased it when their con-centrations were low.
3. Inhibitors of respiratory enzymes, malonic acid, NaCN and monojod aceticacid showed similar dual effects and no specific difference from the above resultswas observed.
4. Triacetine, an important drug for discrimination of acetylcholinesterase did not show any specific effect on the slow potential, but showed a similardual effect.
5. Inorganic ions, KCl, CaCl₂, and others showed similar dual effects.
6. No specific effects but similar dual effects were observed in cases ofadrenaline, noradrenaline, d-tubocurarine, nicotine and TEABr.
7. Glucose showed similar dual effects on the slow potential.
8. The consistent dual effects observed in a variety of drugs are solely pro-duced by the differences of drug concentration. This fact may be explainedby a physico-chemical mechanism occurring at the surface membrane plus thesurrounding interstitium where the slow potential is generated.
9. The dual effects may not be due to the so-called pharmacological effects, but to a physico-chemical mechanism, which was testfied by TEABr.
10. The observation in this paper may probably strengthen the physico-chemical hypothesis on the origin of the slow potential in the spinal cord (1).