The Freezing Point Depression of Mammalian Tissues in Relation to the Question of Osmotic Activity of Cell Fluid

Abstract

The freezing point depression of freshly excised frozen tissues, pulverized in a hydraulic press or in a mortar, is greater than that of plasma. Even at 0°C. the freezing point depression of such homogenates increases significantly with time. Dilution data indicate that such freezing point data are valid. The presence of intact cells has been shown in smears of tissues pulverized in a mortar, but not in smears of those crushed in a hydraulic press. The osmolarity of various diluent solutions affects the calculated osmotic activity of tissue homogenates presumably because of delayed diffusion between the diluent and cell fluid. With a hypertonic NaCl diluent, spuriously low values of tissue osmotic activity are found from calculations assuming instantaneous mixing between homogenates and diluents. The limitations of data from cryoscopic experiments and from tissue-swelling experiments are discussed in relation to the basic question of whether or not cell fluid is isotonic to extracellular fluid.

Ischemic Brain Edema and the Osmotic Gradient between Blood and Brain

“…The osmotic difference be tween blood and brain was �7.6 ± 2.7 mOsm/kg. This finding is consistent with previous studies showing that osmolality of brain tissue is consis tently higher than that of plasma (Brodsky et al, 1956;Stern and Coxon, 1964;To rnheim, 1980). Be cause our study used a slice of intact brain tissue for osmolality measurement, the high values we found are probably not related to autolytic change or to artifacts induced by tissue preparation.…”

A Study of the Osmotic Behavior of the Human Erythrocyte*†

“…measure of colligative properties-of a sample of blood would be expected to be the same after 4. The effects of addition of dry urea rupture of the red cell membranes as it was beSamples of whole blood were mixed one-to-one fore rupture if: 1) the red cell contents before with a solution of NaCl, 5.0 Gm.…”

Concerning the determination of total intracellular concentrations by the cryoscopic method

“…The mean Ft values at zero time for such tissues were then found to be the same as that of the plasma within the sampling error. Brodsky, Appelboom, Dennis, Rehm, Miley & Diamond (1956) have criticized this procedure of extrapolation while ignoring the results with guinea-pig kidney and liver in which it was not required, as well as the experiments in which 0.1 % HgCl2, included in the saline, inhibited the increase of F1 with time when muscle and rat kidney were used. They based their criticism on the supposition that the cell membranes were insufficiently ruptured by the freezing and grinding process, and that complete mixing inside and outside the cells might take a very appreciable time.…”

“…The use of a regression line employing all the available results up to the limit of linearity likewise reduces the variability of such a figure to the smallest level for the available data. The extrapolations used by Brodsky et al (1956) in their Fig. 4, namely joining the first two values (expressed as millimolarities per litre tissue water) in an experiment in order of time and continuing the line to cut the ordinate, makes it obvious that they were unaware of the necessary statistical procedure when dealing with such variable data.…”

“…In the present communication, besides the experiments showing the practically immediate break-down of membrane permeability when frozen and ground tissue is suspended in isotonic saline, there is included a discussion of the data published by Brodsky et al (1956) and what may be deduced therefrom.…”