Biomaterial Database

Reversible changes in the intracellular potassium ion activities and membrane potentials of Aplysia L2-L6 neurones in response to normoxia and hypoxia. 1983

P E Coyer, and J H Halsey, and E R Strong

1. Exposure of 7 L2-L6 neurones to hypoxia for 65 min resulted in hyperpolarization of the membrane potential (EM) from a mean of -49.1 +/- 2.1 to -54.1 +/- 3.6 mV (S.E.). 2. Intracellular potassium ion activities (aiK) increased significantly from 137.7 +/- 4.0 to 155.6 +/- 3.4 mM-K+. This is equivalent to a change in EK from -74.2 mV commensurate with the observed hyperpolarization of 5 mV. 3. The reversibility of these responses was noted by reoxygenating the solution surrounding the ganglion for a period of 55 min. 4. In another group (n = 7) of L2-L6 neurones, the responses in aiK, EM, and EK were slower, although following hypoxia for 90-110 min, similar changes in the levels of these membrane phenomena were recorded. 5. PNa/PK ratios were computed for both L2-L6 groups of neurones using a modified version of the Goldman equation. There were only slight decreases in this ratio with hypoxia, which were not significantly different from the control (normoxia). Therefore, we conclude that this period of hypoxia is capable of stimulating the sodium pump of these cells since the membrane potentials seem to hyperpolarize according to the increase in aiK. However, tonic release of neurotransmitter, which could hyperpolarize these neurones and attract intracellular potassium, cannot be ruled out as an effect of hypoxia.

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
D008839	Microelectrodes	Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)	Electrodes, Miniaturized,Electrode, Miniaturized,Microelectrode,Miniaturized Electrode,Miniaturized Electrodes
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
D004553	Electric Conductivity	The ability of a substrate to allow the passage of ELECTRONS.	Electrical Conductivity,Conductivity, Electric,Conductivity, Electrical
D000332	Aerobiosis	Life or metabolic reactions occurring in an environment containing oxygen.	Aerobioses
D000693	Anaerobiosis	The complete absence, or (loosely) the paucity, of gaseous or dissolved elemental oxygen in a given place or environment. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)	Anaerobic Metabolism,Anaerobic Metabolisms,Anaerobioses,Metabolism, Anaerobic,Metabolisms, Anaerobic
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
D013569	Synapses	Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.	Synapse
D018377	Neurotransmitter Agents	Substances used for their pharmacological actions on any aspect of neurotransmitter systems. Neurotransmitter agents include agonists, antagonists, degradation inhibitors, uptake inhibitors, depleters, precursors, and modulators of receptor function.	Nerve Transmitter Substance,Neurohormone,Neurohumor,Neurotransmitter Agent,Nerve Transmitter Substances,Neurohormones,Neurohumors,Neuromodulator,Neuromodulators,Neuroregulator,Neuroregulators,Neurotransmitter,Neurotransmitters,Substances, Nerve Transmitter,Transmitter Substances, Nerve,Substance, Nerve Transmitter,Transmitter Substance, Nerve