Action of lipid-soluble quaternary ammonium ions on the resting potential of myelinated nerve fibers of the frog

1959 ◽  
Vol 32 ◽  
pp. 381-386 ◽  
Author(s):  
Wolf D. Dettbarn
Keyword(s):  
Quaternary Ammonium ◽  
Nerve Fibers ◽  
Resting Potential ◽  
Ammonium Ions ◽  
Myelinated Nerve ◽  
Myelinated Nerve Fibers ◽  
Quaternary Ammonium Ions

scholarly journals The Inner Quaternary Ammonium Ion Receptor in Potassium Channels of the Node of Ranvier

1972 ◽  
Vol 59 (4) ◽  
pp. 388-400 ◽  
Author(s):  
Clay M. Armstrong ◽  
Bertil Hille
Keyword(s):  
Potassium Channels ◽  
Quaternary Ammonium ◽  
Node Of Ranvier ◽  
Nerve Fibers ◽  
Ammonium Ion ◽  
Ammonium Ions ◽  
Myelinated Nerve ◽  
Quaternary Ammonium Ions ◽  
Activation Gate ◽  
Almost All

Quaternary ammonium ions were applied to the inside of single myelinated nerve fibers by diffusion from a cut end. The resulting block of potassium channels in the node of Ranvier was studied under voltage-clamp conditions. The results agree in almost all respects with similar studies by Armstrong of squid giant axons. With tetraethylammonium ion (TEA), pentyltriethylammonium ion (C5), or nonyltriethylammonium ion (C9) inside the node, potassium current during a depolarization begins to rise at the normal rate, reaches a peak, and then falls again. This unusual inactivation is more complete with C9 than with TEA. Larger depolarizations give more block. Thus the block of potassium channels grows with time and voltage during a depolarization. The block reverses with repolarization, but for C9 full reversal takes seconds at -75 mv. The reversal is faster in 120 mM KCl Ringer's and slower during a hyperpolarization to -125 mv. All of these effects contrast with the time and voltage-independent block of potassium, channels seen with external quaternary ammonium ions on the node of Ranvier. External TEA, C5, and C9 block without inactivation. The external quaternary ammonium ion receptor appears to be distinct from the inner one. Apparently the inner quaternary ammonium ion receptor can be reached only when the activation gate for potassium channels is open. We suggest that the inner receptor lies within the channel and that the channel is a pore with its activation gate near the axoplasmic end.

The electrogenic action of cations on cat spinal motoneurons

1964 ◽  
Vol 161 (982) ◽  
pp. 92-108 ◽  
Keyword(s):  
Membrane Potential ◽  
Quaternary Ammonium ◽  
Resting Potential ◽  
Spinal Motoneurons ◽  
Ammonium Ions ◽  
Quaternary Ammonium Ions ◽  
Ionic Changes ◽  
Intracellular Microelectrodes ◽  
Alkaline Cations ◽  
Very High

Potassium, rubidium, caesium, sodium, lithium, ammonium, tetramethylammonium, tetraethylammonium and choline ions were injected into cat spinal motoneurons electrophoretically through intracellular microelectrodes, and their effects on the resting potential were compared. Potassium and rubidium injections did not alter the resting potential to any appreciable extent, while depolarization to different degrees was produced by injections of caesium, sodium and lithium. It is suggested that the resting motoneuronal membrane is permeable to the alkaline cations in the order K ≑ Rb > Cs > Na ≑ Li. However, the depolarizing action of sodium and lithium injections varied considerably according to the preinjection level of the resting potential, and eventually was minimal when the membrane potential was very high, about —80 mV. Reasons for such insensitivity of the high resting potential to the ionic changes produced by the injections are discussed. After the injections of the alkaline cations there was recovery from the depressed membrane potential within 30 sec to 14 min; but ammonium and quaternary ammonium ions produced an irreversible depolarization which tended to become progressive with successive injections of these cations.

scholarly journals THE SUBMICROSCOPIC ORGANIZATION OF AXON MATERIAL ISOLATED FROM MYELIN NERVE FIBERS

1953 ◽  
Vol 98 (3) ◽  
pp. 269-276 ◽  
Author(s):  
E. De Robertis ◽  
C. M. Franchi
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Phase Contrast ◽  
Nerve Fibers ◽  
Myelinated Nerve ◽  
Myelinated Nerve Fibers ◽  
Dense Granules ◽  
Small Clusters ◽  
Membranous Material ◽  
The Way

A technique has been developed for the extrusion of axon material from myelinated nerve fibers. This material is then compressed and prepared for observation with the electron microscope. All the stages of preparation and purification of the axon material can be checked microscopically and in the present paper they are illustrated with phase contrast photomicrographs. Observation with the electron microscope of the compressed axons showed the presence of the following components: granules, fibrils, and a membranous material. Only the larger granules could be seen with the ordinary microscope. A considerable number of dense granules were observed. Of these the largest resemble typical mitochondria of 250 mµ by 900 mµ. In addition rows or small clusters of dense granules ranging in diameter from 250 to 90 mµ were present. In several specimens fragments of a membrane 120 to 140 A thick and intimately connected with the axon were found. The entire axon appeared to be constituted of a large bundle of parallel tightly packed fibrils among which the granules are interspersed. The fibrils are of indefinite length and generally smooth. They are rather labile structures, less resistant in the rat than in the toad nerve. They varied between 100 and 400 A in diameter and in some cases disintegrated into very fine filaments (less than 100 A thick). The significance is discussed of the submicroscopic structures revealed by electron microscopy of the material prepared in the way described.

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