Ionic conductance associated with electrical activity of guinea-pig red nucleus neurones in vitro.
Intracellular recordings were made from red nucleus (r.n.) neurones in guinea-pig slice preparations in vitro. In the control solution, a fast action potential was elicited by a depolarizing current pulse. This fast action potential was abolished by tetrodotoxin (TTX). When tetraethylammonium (TEA) was added to the perfusing solution, a TTX-resistant slow action potential was elicited by a large depolarizing current pulse. This TTX-resistant slow action potential was abolished by Co2+ or Mn2+. In the control solution, the action potential was followed by a fast and a slow after-hyperpolarization (a.h.p.). The fast a.h.p. was abolished by TEA. The amplitude of the fast a.h.p. was dependent on the extracellular K+ concentration. The slow a.h.p. was reversibly abolished by Co2+ or Mn2+. The reversal potential of the slow a.h.p. was dependent on the extracellular K+ concentration. When the membrane potential was hyperpolarized, a time-dependent inward rectification was observed. This inward rectification was inhibited by Cs+ but not by Ba2+, TTX, TEA or Co2+. It is concluded that the fast action potential is produced by a voltage-dependent Na+ conductance, the TTX-resistant slow action potential is produced by a voltage-dependent Ca2+ conductance, the fast a.h.p. is produced by a voltage-dependent K+ conductance, the slow a.h.p. is produced by a Ca2+-activated K+ conductance and the inward rectification is produced by a time-dependent inward rectifier in r.n. neurones.
M
M
Kubota
M
M
Nakamura
N
N
Tsukahara
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002586:Cesium / Q000494:pharmacology; D003035:Cobalt / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007473:Ion Channels / Q000502:physiology*; D008564:Membrane Potentials; D009474:Neurons / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology; D012012:Red Nucleus / Q000166:cytology*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors
D007473:Ion Channels; D013757:Tetraethylammonium Compounds; D002586:Cesium; D003035:Cobalt; D013779:Tetrodotoxin; D019789:Tetraethylammonium; D011188:Potassium