Erythrocyte and ghost cytoplasmic resistivity and voltage-dependent apparent size

Abstract

Particle resistivity is explicitly included in the equations relating volume to voltage pulse, in electronic cell sizing or resistive pulse spectroscopy (RPS). It has long been known that in high electric fields cell resistivity decreases as the membrane undergoes dielectric breakdown. At sufficiently high electric field strengths, well past dielectric breakdown, the red cell membrane becomes electrically transparent, or nearly so, and apparent cell size becomes essentially a function of the cytoplasmic resistivity. Electronic cell sizing is traditionally carried out at low electric field strengths, and corrections made for the influence of cell shape by use of the Laplace equation. We find the Laplace solution to be still applicable at very high electric field strengths for purposes of calculating specific cytoplasmic resistivity from RPS measurements. Our value for discocytes, 220 omega X cm, is in good agreement with published results obtained by other researchers using other techniques. We have also applied these same procedures to determine the time course of voltage-dependent resistivity changes in ghosts and intact spherocytes, during the first 5 min after suspension in hypotonic medium. We believe these to be the first explicit calculations of particle specific resistivity from post-dielectric-breakdown apparent size, using traditional electronic sizing techniques.

Radio-mitigation effect of poly-MVA after exposure to an acute dose of gamma radiation

“…Osmotic fragility can be defined as the sensitivity to change in the osmotic pressure characteristic of red blood cells. It is considered to be a function of the osmotic pressure gradient between intra-and extracellular media, initial surface area to volume ratio, membrane tension of haemolysis and ionic content of the cell [28]. It has been found to be altered in various pathological conditions, such as liver and blood diseases.…”

Response to Pilwat and Zimmermann

“…45-60 s post exposure to hemolytic medium) if normal (rather than slow) flow is employed. This is clearly shown in reference 2, and has been discussed in previous publications (3), and referenced in (1). (By appropriate manipulation of medium conditions, quite accurate steady state osmotic fragility percentages can be determined in this way, as well.…”

“…We would first like to thank Drs. Pilwat and Zimmermann for pointing out that it was a technical problem in one of our resistive particle sizing experiments that led to the experimental observation of "disappearing ghosts" (1). We also have found that a problem existed with this particular experiment.…”

“…A final comment is in order on the explanation offered by Pilwat and Zimmermann for the (real or apparent) lower value of the internal resistivity of resealed ghosts, as compared with that of the external medium, especially in the light of the results of MacGregor and Tobias, 1972 ([4]; also referenced in [1]). We agree with the observation itself.…”

Comments on "Erythrocyte and ghost cytoplasmic resistivity and voltage-dependent apparent size"

“…Dear Sirs, Akeson and Mel (1983) recently reported on the determination of the cytoplasmic resistivity of human red blood cells and ghost cells by electronic cell sizing (resistive pulse spectroscopy). The method is based on the experimental finding of Zimmermann et al (1973Zimmermann et al ( , 1974 that the voltage signal generated by a cell during its passage through an electric field changes once the breakdown 3X _ voltage of the membrane is exceeded.…”