Characterization of slow postsynaptic K + current of Aplysia LUQ neurons in culture

• Published in: Brain research Vol. 629; no. 1; pp. 88 - 94
• Main Authors: Yanaura, Mamiko, Nakashima, Michio, Yamada, Satoshi, Shiono, Satoru
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 26.11.1993; Amsterdam Elsevier; New York, NY
• Subjects: 8-Bromo Cyclic Adenosine Monophosphate - pharmacology; Action Potentials; Animals; Aplysia; Atropine - pharmacology; Biochemistry. Physiology. Immunology; Biological and medical sciences; Cells, Cultured; Culture; Egtazic Acid - pharmacology; Evoked Potentials - drug effects; FMRFamide; Fundamental and applied biological sciences. Psychology; Guanosine 5'-O-(3-Thiotriphosphate) - pharmacology; Invertebrates; Mollusca; Neurons - drug effects; Neurons - physiology; Neuropeptides - pharmacology; Physiology. Development; Potassium - pharmacology; Quaternary Ammonium Compounds - pharmacology; Serotonin - pharmacology; Slow K + current; Synapse; Synapses - physiology; Tubocurarine; Aplysia; Slow K + current; Synapse; Culture; FMRFamide; Aplysia californica; Electrophysiology; Nervous system; Gastropoda; Ionic current; Neuropeptide; In vitro; Synaptic transmission; Neurotransmitter; Acetylcholine; Postsynaptic potential; Invertebrata; Mollusca; FMRF amide; Potassium
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/0006-8993(93)90485-6

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 phenyltrimethylamminium, an ACh antagonist, on the postsynaptic, ACh-, and FMRFamide-induced currents, clearly indicating that the neurotransmitter used in the cultured synapses was not ACh.