Biomaterial Database

Analysis of the modulation by serotonin of a voltage-dependent potassium current in sensory neurons of Aplysia. 1994

J A White, and D A Baxter, and J H Byrne

Department of Neurobiology and Anatomy, University of Texas Medical School, Houston 77225.

Potassium currents in pleural sensory neurons of Aplysia were studied under control conditions and in the presence of serotonin (5-HT). Using pharmacological techniques we isolated a current that we refer to as IK,V. Although it is not known whether IK,V represents a distinct type of membrane channel, we described its properties using a Hodgkin-Huxley type model. The effects of 5-HT on IK,V were complex. 5-HT decreased by 50% the steady-state magnitude (Iss) of IK,V in response to a voltage-clamp pulse from -50 mV to +20 mV. In addition, 5-HT significantly slowed both activation kinetics (the time constant of activation was increased by 29% at +20 mV) and inactivation kinetics (the time constant of inactivation was increased by 518% at +20 mV). Mathematical descriptions of IK,V in control conditions and in the presence of 5-HT were used to estimate the relative contribution of serotonergic modulation of IK,V to the total 5-HT-induced modulation of membrane currents. Effects of 5-HT on IK,V account for more than 87% of the 5-HT-induced reduction in outward current during the first 20 ms of a voltage-clamp pulse to +20 mV. This result implies that 5-HT exerts many of its effects on spike width in sensory neurons via modulation of IK,V. Effects of 5-HT on IK,V are consistent with a model in which the maximal conductance underlying the current is decreased by 50%, and the rate constants between open and closed states of both the activation and inactivation processes are diminished in magnitude across all membrane potentials.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
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
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D009475	Neurons, Afferent	Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.	Afferent Neurons,Afferent Neuron,Neuron, Afferent
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D004553	Electric Conductivity	The ability of a substrate to allow the passage of ELECTRONS.	Electrical Conductivity,Conductivity, Electric,Conductivity, 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
D001048	Aplysia	An opisthobranch mollusk of the order Anaspidea. It is used frequently in studies of nervous system development because of its large identifiable neurons. Aplysiatoxin and its derivatives are not biosynthesized by Aplysia, but acquired by ingestion of Lyngbya (seaweed) species.	Aplysias
D001703	Biophysics	The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.	Mechanobiology
D012701	Serotonin	A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.	5-HT,5-Hydroxytryptamine,3-(2-Aminoethyl)-1H-indol-5-ol,Enteramine,Hippophaine,Hydroxytryptamine,5 Hydroxytryptamine