Two distinct propagating regenerative potentials in a single ethanol-treated axon.
Superfusion of the cockroach (Periplaneta americana) giant axon by ethanol (0.5-2%) produces conditions which allow the generation and active propagation of two kinds of regenerative potentials. The classical action potential with a threshold at about 30 mV above resting potential, an amplitude of about 105 mV, a duration of 1-2 ms, and a conduction velocity of 3-6 m/s. A smaller depolarizing potential (SDP) with a threshold of 5-15 mV above resting level, an amplitude of 10-30 mV, a duration of several hundred ms and a conduction velocity of 0.1-0.6 m/s. The SDP is associated with a small increase in conductance (10-15%), and is abolished by tetrodotoxin (10(-6) M) or by removing extracellular sodium. The amplitude of the SDP slightly increases when the extracellular Ca2+ concentration is elevated and is reduced at low (Ca2+)o concentration; however, it is not blocked in a solution containing high Mg2+ (19 mM), low Ca2+ (1 mM) concentrations, indicating that inward Ca2+ current is not required for the generation of SDP.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology; D004558:Electric Stimulation; D000431:Ethanol / Q000494:pharmacology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D010526:Periplaneta; D012964:Sodium / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D000431:Ethanol; D013779:Tetrodotoxin; D012964:Sodium; D002118:Calcium