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Biomedical subjects

E Engel

Publications and source records attributed to E Engel.

At least 199 records · Page 11Linked to original sources
PubMed1972

The interpretation of current-voltage relations recorded from a spherical cell with a single microelectrode.

An analysis is presented of the displacement of potential recorded when one microelectrode is used both to apply current to and record potential from a spherical cell. There are three significant components of the displacement in potential: a component produced inside the microelectrode, a time-independent component representing the spatially nonuniform flow of current in the immediate vicinity of the microelectrode, and a time-dependent spatially uniform component representing the average potential across the cell membrane. The second component describes changes in the potential across the cell membrane as well as potential drops in the interior of the cell, the importance of each factor being dependent on the location of the electrode. Simple expressions, derived by a theoretical treatment, are given for each component of potential. The implications for the interpretation of experimental results determined with the "single-electrode bridge" technique are discussed and an optimal balancing procedure is suggested.

Cell Membrane↗
PubMed1970

XYY and crime.

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Adult↗
PubMed1970

The spatial variation of membrane potential near a small source of current in a spherical cell.

A theoretical analysis is presented of the change in membrane potential produced by current supplied by a microelectrode inserted just under the membrane of a spherical cell. The results of the analysis are presented in tabular and graphic form for three wave forms of current: steady, step function, and sinusoidal. As expected from physical reasoning, we find that the membrane potential is nonuniform, that there is a steep rise in membrane potential near the current microelectrode, and that this rise is of particular importance when the membrane resistance is low, or the membrane potential is changing rapidly. The effect of this steep rise in potential on the interpretation of voltage measurements from spherical cells is discussed and practical suggestions for minimizing these effects are made: in particular, it is pointed out that if the current and voltage electrodes are separated by 60 degrees , the change in membrane potential produced by application of current is close to that which would occur if there were no spatial variation of potential. We thus suggest that investigations of the electrical properties of spherical cells using two microelectrodes can best be made when the electrodes are separated by 60 degrees .

Cell Membrane↗