The Teorell membrane oscillator--a complete nerve model.

U F Franck

doi:10.3109/03009738009179197

Home/Archive/PubMed

PubMed · 6262982

The Teorell membrane oscillator--a complete nerve model.

U F Franck

View original source ↗Export metadata ↓

Abstract

The membrane oscillator discovered by T. Teorell in 1954 (10) is one of the most remarkable kinetic systems exhibiting spontaneous periodic behaviour under constant environmental conditions. It can be shown and demonstrated experimentally that the intrinsic reason for the occurrence of oscillations in the Teorell oscillator, like in other physicochemical and biological oscillatory systems, is an appropriate antagonistic action of a labilizing positive and a recovering stabilizing negative feedback. Each kind of feedback causes a group of characteristic temporal phenomena, which are observed in all oscillatory systems including the living excitable nerve such as: instability, bistability, excitability, propagation of exitation and recovery, refractoriness, abolition, accommodation etc..

Explore related subjects

Cell Membrane Permeability Electrolytes Ion Channels Kinetics Membrane Potentials Membranes, Artificial Models, Neurological Synaptic Transmission Journal Article

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

U F Franck. 1980. The Teorell membrane oscillator--a complete nerve model.. https://doi.org/10.3109/03009738009179197

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Does the calcein-AM method assay the total cellular 'labile iron pool' or only a fraction of it?

The calcein-AM (calcein-acetoxymethyl ester) method is a widely used technique that is supposed to assay the intracellular 'labile iron pool' (LIP). When cells in culture are exposed to this ester, it passes the plasma membrane and reacts with cytosolic unspecific esterases. One of the reaction products, calcein, is a fluorochrome and a hydrophilic alcohol to which membranes are non-permeable and which, consequently, is retained within the cytosol of cells. Calcein fluorescence is quenched following chelation of low-mass labile iron, and the degree of quenching gives an estimate of the amounts of chelatable iron. However, a requirement for the assay to be able to demonstrate cellular LIP in total is that such iron be localized in the cytosol and not in a membrane-limited compartment. For some time it has been known that a major part of cellular, redox-active, labile, low-mass iron is temporarily localized in the lysosomal compartment as a result of the autophagic degradation of ferruginous materials, such as mitochondrial complexes and ferritin. Even if some calcein-AM may escape cytosolic esterases and enter lysosomes to be cleaved by lysosomal acidic esterases, the resulting calcein does not significantly chelate iron at <pH 5. In the present study we show that the calcein-AM method does not capture lysosomal low-mass iron and, therefore, that the method seriously underestimates total cellular labile iron.

Cell Membrane Permeability↗

PubMed2007

High-throughput liberation of water-soluble yeast content by irreversible electropermeation (HT-irEP).

The article describes a high-throughput method for the liberation of water-soluble cell contents by exploiting the phenomenon of irreversible membrane electropermeation (HT-irEP). The method is exemplified in recombinant proteins and plasmid liberation from yeast Saccharomyces cerevisiae on the detectable level. Obtained extracts are pure enough to be readily applied for further analytical analysis such as enzyme assay, PCR, and so on. From the same HT-irEP extract, one can measure activity of the target protein and perform amplification of the corresponding gene from the DNA vector by PCR for recombinant protein with intracellular expression. Therefore, the method is suitable for the high-throughput screening (HTS) of yeast libraries where extracellular expression of recombinant protein is problematic. The method can be easily automated and integrated into existing HTS systems.

Cell Membrane Permeability↗

PubMed2007

Expression and characterization of human growth hormone-Fc fusion proteins for transcytosis induction.

The major obstacle for oral delivery of administered therapeutic proteins is malabsorption in the intestine. This malabsorption could be overcome by induction of neonatal FcRn [Fc (CH2 and CH3 domains of human IgG1 antibody) receptor]-mediated transcytosis in the intestine using recombinant fusion of CH2 and CH3 moieties of human IgG to a therapeutic protein. To this end we developed recombinant hGH (human growth hormone) fused to the N-terminus of Fc moieties [CH2-CH3 or h (hinge)-CH2-CH3] from human IgG1. These recombinant proteins secreted by the methylotrophic yeast Pichia pastoris functionally induced secretion of insulin-like growth factor 1 by HepG2 cells in the response to hGH moiety in the fusion proteins. In a transport study using polarized T84 cells, 3.7% of added dimeric hGH-h-Fc was transported in the apical-to-basolateral direction within 1 h by FcRn-mediated transcytosis of 1 cm(2) monolayers. However, transport of monomeric hGH-Fc (only 0.43%) was much less effective, yet its transport was 2.3 times higher than that of hGH. Finally, we concluded that, upon recombinant fusion, maintenance of dimeric structure of Fc moieties is crucial for the induction of FcRn-mediated transcytosis.

Cell Membrane Permeability↗