The Response of Duck Erythrocytes to Hypertonic Media

Abstract

The addition of a hypertonic bathing medium to duck erythrocytes results in an initial instantaneous phase of osmotic shrinkage and, when the [K]o of the hypertonic solution is larger than "normal," in a second, more prolonged phase, the volume regulatory phase. During the latter, which also requires extracellular Na, the cells swell until they approach their initial isotonic volume. The increase in cell volume during the volume regulatory phase is accomplished by a gain in the cell content of K, C1, and H 2 0. There is also a smaller increase in the Na content of the cell. Potassium is accumulated against an electrochemical gradient and is therefore actively transported into the cell. This accumulation is associated with an increase, although dissimilar, in both K influx and efflux. Changes in cell size during the volume regulatory phase are not altered by 10 -4 M ouabain, although this concentration of ouabain does change the cellular cation content. The response is independent of any effect of norepinephrine. The changes in cell size during the volume regulatory phase are discussed as the product of a volume controlling mechanism identical in principle to the one reported in the previous paper which controls cell volume in hypotonic media. Similarly, this mechanism can regulate cell size, when the Na-K exchange, ouabain-inhibitable pump mechanism is blocked.

Functional Separation of the Na-K Exchange Pump from the Volume Controlling Mechanism in Enlarged Duck Red Cells

“…Perhaps most interesting, however, is the presence of an enormous bidirectional increase in ouabain-insensitive Na and K movements (often > 100 mmol/ literoNc/h). These movements resemble in many respects those seen when duck red cells incubate in hypertonic media (2). The control of cation content and movement in minimal volume cells is the subject of a future publication.…”

“…The procedures for obtaining LSS cells ([K], 110 mmol/liter, [Na], -5 mmol/liter, and [Cl], 51 mmol/liter) has been described elsewhere (1,2).…”

“…The low-Na (choline) medium has the followingcomposition: 2 mM MgC1 2 , 1 mM CaC2l, 2.5 mM KH 2 PO 4 , 28 mM choline bicarbonate (Matheson, Coleman, and Bell, Norwood, Ohio), 121 mM choline Cl, 20 mM dextrose, and 2.5 g/100 ml albumin. All procedures during the experimental period were identical to those used previously (5, 1) including incubating the cells at 41°C in an atmosphere of 95 % 02 and 5 % CO 2 .…”

“…Duck erythrocytes can readjust their size by utilizing a ouabain-insensitive "volume controlling mechanism" (1,2). This mechanism regulates the cation content of cells; the changes in cation content produce, in turn, isosmotic shifts in cell water and changes in cell size (3).…”

Volume regulation by flounder red blood cells in anisotonic media

“…The volume THE JOURNAL OF GENERAL PHYSIOLOGY ' VOLUME 69, 1977 ' pages 537-552 537 on May 12, 2018 jgp.rupress.org Downloaded from http://doi.org/10. 1085/jgp.69.5.537 Published Online: 1 May, 1977 538 THE JOURNAL OF GENERAL PHYSIOLOGY " VOLUME 69 ' 1977 regulatory response of duck erythrocytes was studied by Kregenow (4,5). These cells were shown to rely almost solely upon net inorganic ion fluxes as a means of effecting net water flow during volume regulation.…”