Characterization of slow postsynaptic K+ current of Aplysia LUQ neurons in culture.
We have characterized the slow inhibitory synaptic connection between an left upper quadrant (LUQ) neuron and neuron L10, L12 or L13 in culture. A slow postsynaptic outward current in the LUQ neuron was elicited by repetitive firing of the co-cultured cholinergic neuron L10 as well as neuron L12 or L13 which were not cholinergic but FMRFamide synthesizing neurons. This outward current was due to an increase in K+ conductance and was relatively insensitive to external application of tetraethylammonium and 4-aminopyridine. We also investigated the effects of injection of a guanosine 5'-triphosphate (GTP) analogue into the LUQ neuron and extracellular application of serotonin and an adenosine 3',5'-cyclic monophosphate (cAMP) analogue on the current. In all the investigated properties, no significant difference was found among neuron L10, L12 and L13 as a presynaptic neuron. The slow postsynaptic current appeared to be virtually identical to the FMRFamide or acetylcholine (ACh)-induced K+ current reported in vivo, which resembled the 'S' current in Aplysia sensory neurons. We performed experiments to see the effect of phenyltrimethylammonium, an ACh antagonist, on the postsynaptic, ACh-, and FMRFamide-induced currents, clearly indicating that the neurotransmitter used in the cultured synapses was not ACh.
Yanaura
M
M
Central Research Laboratory, Mitsubishi Electric Corporation, Hyogo, Japan.
Nakashima
M
M
Yamada
S
S
Shiono
S
S
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000200:Action Potentials; D000818:Animals; D001048:Aplysia; D001285:Atropine / Q000494:pharmacology; D002478:Cells, Cultured; D004533:Egtazic Acid / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects*; D019835:FMRFamide; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009479:Neuropeptides / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D012701:Serotonin / Q000494:pharmacology; D013569:Synapses / Q000502:physiology*; D014403:Tubocurarine
D009479:Neuropeptides; D000644:Quaternary Ammonium Compounds; D015124:8-Bromo Cyclic Adenosine Monophosphate; D012701:Serotonin; C001420:3-hydroxyphenyltrimethylammonium; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D004533:Egtazic Acid; D019835:FMRFamide; D001285:Atropine; D011188:Potassium; D014403:Tubocurarine