Biomaterial Database

Ionic differences between somatic and axonal action potentials in snail giant neurones. 1972

F Wald

1. The ionic requirements of the somatic and axonal action potentials of ;H' neurones of the snail Cryptomphallus aspersa were studied using intracellular micro-electrodes.2. The overshoot of the somatic action potential increased by 10 mV for a tenfold increase in [Ca(2+)](o). In calcium-free media the action potential decreased gradually to values of 50 to 90% of the control and they could be completely eliminated with 2 mM-EGTA. The maximum rate of rise also varied with [Ca(2+)](o).3. After 2 hr in sodium-free solution the somatic action potential decreased 6% in overshoot and 24% in rate of rise.4. The somatic action potential was not affected by TTX, 5 x 10(-6) g/ml. Procaine, 18 mM, reduced its rate of rise but did not eliminate it whereas 30 mM-CoCl(2) did.5. The size of the axonal action potential increased with increased [Na(+)](o), but decreased with an increase in [Ca(2+)](o).6. Procaine, 18 mM, abolished the axonal action potential whereas it was not affected by TTX, 5 x 10(-6) g/ml., nor, usually, by 30 mM-CoCl(2).7. The results obtained by studying the compound action potential of the nerves were similar to those from axonal action potentials.8. The possibility that the somatic action potential is mainly calcium dependent while the axonal action potential is mainly produced by sodium is discussed.

UI	MeSH Term	Description	Entries
D007094	Imides	Organic compounds containing two acyl groups bound to NITROGEN.	Imide
D008274	Magnesium	A metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
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
D011343	Procaine	A local anesthetic of the ester type that has a slow onset and a short duration of action. It is mainly used for infiltration anesthesia, peripheral nerve block, and spinal block. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1016).	Anuject,Geriocaine,Gerokit,Hewedolor-Procain,Lophakomp-Procain N,Novocain,Novocaine,Procain Braun,Procain Jenapharm,Procain Rödler,Procain Steigerwald,Procain curasan,Procaina Serra,Procaine Hydrochloride,Pröcaine chlorhydrate Lavoisier,Röwo Procain,procain-loges,Hydrochloride, Procaine
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D003035	Cobalt	A trace element that is a component of vitamin B12. It has the atomic symbol Co, atomic number 27, and atomic weight 58.93. It is used in nuclear weapons, alloys, and pigments. Deficiency in animals leads to anemia; its excess in humans can lead to erythrocytosis.	Cobalt-59,Cobalt 59
D004987	Ethers	Organic compounds having two alkyl or aryl groups bonded to an oxygen atom, as in the formula R1–O–R2.
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
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