Osmotic properties of human red cells

Abstract

When an osmotic pressure gradient is applied to human red cells, the volume changes anomalously, as if there were a significant fraction of "nonosmotic water" which could not serve as solvent for the cell solutes, a finding which has been discussed widely in the literature. In 1968, Gary-Bobo and Solomon (J. Gen. Physiol. 52:825) concluded that the anomalies could not be entirely explained by the colligative properties of hemoglobin (Hb) and proposed that there was an additional concentration dependence of the Hb charge (ZHb). A number of investigators, particularly Freedman and Hoffman (1979, J. Gen. Physiol. 74:157) have been unable to confirm Gary-Bobo and Solomon's experimental evidence for this concentration dependence of ZHb and we now report that we are also unable to repeat the earlier experiments. Nonetheless, there still remains a significant anomaly which amounts to 12.5 +/- 0.8% of the total isosmotic cell water (P much less than 0.0005, t test), even after taking account of the concentration dependence of the Hb osmotic coefficient and all the other known physical chemical constraints, ideal and nonideal. It is suggested that the anomalies at high Hb concentration in shrunken cells may arise from the ionic strength dependence of the Hb osmotic coefficient. In swollen red cells at low ionic strength, solute binding to membrane and intracellular proteins is increased and it is suggested that this factor may account, in part, for the anomalous behavior of these cells.

An improved cryopreservation method for a mouse embryonic stem cell line

“…V b was determined to be 49.8% of isosmotic cell volume. This value is comparable to the V b of human spermatozoa (50% of isosmotic cell volume) [54] and human red blood cells (43% of isosmotic cell volume) [55], and is notably higher than the range of V b measured for other stem cells, including human umbilical cord blood CD34+ cells (27% and 32% of their respective isosmotic cell volumes) [13;56], and human bone marrowderived hematopoietic progenitor cells (20.5% of isosmotic cell volume) [57].…”

Determination of extracellular/intracellular fluid ratios from magnetic resonance images: Accuracy, feasibility, and implementation

“…With one exception, the maximum difference in hematocrit values between any two samples from each group was 0.7%. This accuracy is similar to that obtained by other authors (20). The hematocrits ranged between 75 and 93%, emulating fluid distributions that typically occur in adult CNS tissue.…”

Combined use of micropipette aspiration and perifusion for studying red blood cell volume regulation

“…However, like other cells, RBCs do have a variety of ion transport systems (1), although these systems are mostly active in young RBCs (4,8); fully mature circulating RBC behave closely to that expected for an osmometer (i.e., stable volume changes after anisotonic exposures). The RBC may have a volume fraction of nonosmotically active cell components, the nature of which have been detailed elsewhere (27). In this paper, by calculating the expected volume response with equation 2, we also assumed that an inactive volume exists and found very close agreement between the measured and calculated volume responses at 400, 200, and 130 mOsm (Fig.…”