Regulatory volume decrease in COS-7 cells at 22 °C and its influence on the Boyle van’t Hoff relation and the determination of the osmotically inactive volume

Abstract

Cryobiological analyses assume that the direction and rate of water movements across cell membranes and equilibrium cell volumes are determined solely by differences in the chemical potentials of intra- and extracellular water. A consequence of this assumption is that cells obey the Boyle van’t Hoff (BvH) law which states that cell volumes are a linear function of reciprocal osmolality. Extrapolation of the BvH plot to infinite osmolality yields a quantity b, the fractional volume of the cell occupied by solids. In many cells, however, a cell volume excursion above the isotonic volume initiates an energy-requiring response that causes the swollen cells to shrink back to or towards isotonic volume. It is referred to as Regulatory Volume Decrease (RVD). We have observed a strong RVD in COS-7 cells. If not eliminated by keeping exposure times short, this RVD produces a b that is 60% too high (0.48 vs. 0.30) These results indicate the importance of examining cells for volume regulatory mechanisms before performing measurements to determine their osmotic parameters.

Fatigue damage to pig erythrocytes during repeated swelling and shrinkage

“…Upon addition of hypotonic solution, cells undergo abrupt swelling, at which point the volume of the cells will be regulated by the RVD [10,11]. In the present work, we presented a similar result for pig erythrocytes (Fig.…”

“…The cell volume excursion may then cause an irreversible change and thus damage the cells [5][6][7][8][9]. The volume of cells can be modified by the procedure of regulatory volume decrease (RVD) after acute swelling or by the procedure of regulatory volume increase (RVI) after acute shrinkage [10,11]. Consequently, a new volume set point for cells appears after major swelling and shrinkage.…”

Passive coupling of membrane tension and cell volume during active response of cells to osmosis

“…Our verification of the PBVH relation yields two surprising results: First, we find that it holds for a very large range of osmotic pressures in HeLa cells, larger than previously tested. Second, the V OI represents a smaller proportion of V 0 [only 10%, compared to values between 7 and 50% in other studies (36,44,45)]. As the V OI is obtained from a linear fit, the range of data and the formula used for the fit can strongly change the V OI .…”

Meta-analysis and experimental re-evaluation of the Boyle van ‘t Hoff relation with osmoregulation modelled by linear elastic principles and ion-osmolyte leakage

“…However, it is interesting to note how observed mechanisms for specific cell types match up with how well a specific model (that assumes those mechanisms) fits the respective data. The leak model notably excels at predicting the osmotic behavior of HeLa cells (dataset {9,1}), Chondrocytes (dataset {1,3}), and kidney fibroblasts (dataset {9,1}), which are thought to use mechanosensitive gates to release osmolytes [54,59,62]. Interestingly, some chondrocytes datasets appear linear (datasets {2,4},{8,2}) while others were very nonlinear (dataset {1,3}) potentially due to species differences but also the range of osmotic challenge.…”