Bursting firing of action potentials in central snail neurons elicited by d-amphetamine: role of the electrogenic sodium pump.
The effects of d-amphetamine on central neurons were studied electrophysiologically in the identifiable RP4 neuron of the African snail, Achatina fulica Ferussac. d-Amphetamine elicited bursting activity from the central RP4 neuron in a concentration-dependent manner. The bursting activity was not blocked in a high magnesium (30 mM) medium, or after a continuous perfusion of propranolol, prazosin, haloperidol, phenobarbital, hexamethonium, d-tubocurarine, atropine, or calcium-free solution containing EDTA or verapamil. These results suggested that the bursting activity elicited by d-amphetamine was not due to: (1) the synaptic effects of neurotransmitters; or (2) the cholinergic or adrenergic receptors of the excitable membrane. However, the bursting activity elicited by d-amphetamine was blocked in the presence of ouabain or in the medium containing potassium-free, low sodium solutions. d-Amphetamine did not elicit the bursting activity of the LP4 neuron in the same ganglia preparation, and did not alter the GABA-elicited currents of the snail neuron. It is concluded, therefore, that d-amphetamine induced a potassium- and sodium-dependent bursting activity of central neurons. The bursting activity of the central neuron may be associated with the sodium pump of the neuron.
Tsai
M C
MC
Department of Pharmacology, College of Medicine, National Taiwan University, Taipei, R.O.C.
Chen
Y H
YH
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D003913:Dextroamphetamine / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004492:Edetic Acid / Q000494:pharmacology; D004947:Esophagus / Q000378:metabolism; D006220:Haloperidol / Q000494:pharmacology; D018738:Hexamethonium / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D010042:Ouabain / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010634:Phenobarbital / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D012908:Snails; D012964:Sodium / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects / Q000502:physiology*; D013696:Temperature; D014403:Tubocurarine / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
D018738:Hexamethonium; D010042:Ouabain; D001285:Atropine; D004492:Edetic Acid; D012964:Sodium; D011433:Propranolol; D014700:Verapamil; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium; D006220:Haloperidol; D011188:Potassium; D003913:Dextroamphetamine; D014403:Tubocurarine; D011224:Prazosin; D010634:Phenobarbital