Inhibitory effects of aromatic oligopeptides on the excitability of identifiable giant neurones of an African giant snail (Achatina fulica Férussac). 1979

H Takeuchi, and H Tamura, and A Sakai

Effects of an aromatic tripeptide, L-Lys-L-Phe-L-Tyr and its related dipeptides on the excitability of two identifiable giant neurones (the TAN, tonically autoactive neurone and the PON, periodically oscillating neurone) in the suboesophageal ganglia of the African giant snail, Achatina fulica Férussac, were examined. Of 33 substances examined, three aromatic oligopeptides showed a marked inhibitory effect on the TAN excitability. The critical concentrations of these substances in bath application were: L-Lys-LPhe-L-Tyr (6.6 x 10(-6) approximately 2.2 x 10(-5) M), L-Phe-L-Tyr (9.1 x 10(-6) approximately 3.0 x 10(-5) M) and L-Phe-L-Trp (2.4 x 10(-5) approximately 7.3 x 10(-5) M). The microdrop application (100 micron in diameter) of a solution of the three inhibitory oligopeptides on the TAN surface hyperpolarized the TAN membrane potential and eliminated the spike discharges, in both the physiological and the chloride-free (replaced with acetate) conditions. The current-voltage relationships (I-V curve) of the TAN neuromembrane were measured by the injection of a transmembrane triangular current. The TAN I-V curve measured in the presence of L-Lys-L-Phe-L-Tyr or L-Phe-L-Trp was almost concordant to that of the normal state, if the two I-V curves were superimposed using the firing level as the reference point. The same three aromatic oligopeptides also showed an inhibitory effect on the PON excitability. The critical concentrations needed to produce the effects were much higher than those in the case of the TAN.

UI MeSH Term Description Entries
D008564 Membrane Potentials The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization). Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D009474 Neurons The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM. Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D009842 Oligopeptides Peptides composed of between two and twelve amino acids. Oligopeptide
D004558 Electric Stimulation Use of electric potential or currents to elicit biological responses. Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D012908 Snails Marine, freshwater, or terrestrial mollusks of the class Gastropoda. Most have an enclosing spiral shell, and several genera harbor parasites pathogenic to man. Snail
D013329 Structure-Activity Relationship The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups. Relationship, Structure-Activity,Relationships, Structure-Activity,Structure Activity Relationship,Structure-Activity Relationships
D066298 In Vitro Techniques Methods to study reactions or processes taking place in an artificial environment outside the living organism. In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In

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