The Reponse of Duck Erythrocytes to Norepinephrine and an Elevated Extracellular Potassium

Abstract

This paper presents evidence that duck erythrocytes regulate their size in isotonic media by utilizing a previously reported "volume-controlling mechanism." Two different experimental situations are examined. In the first, cells enlarge in a solution containing norepinephrine and an elevated [K]o; and in the second, enlarged cells shrink to their original size if the norepinephrine and excess potassium are removed. As the erythrocytes enlarge, K, Cl, and H2O accumulate. Shrinkage, in contrast, is accompanied by the controlled loss of K, Cl, and H2O. These changes and the associated changes in membrane permeability resemble those reported previously when duck erythrocytes incubate in anisotonic media. There cells, after first shrinking or swelling, utilize a "volume-controlling mechanism" to reestablish their original size. The mechanism regulates cell size by adjusting the total number of osmotically active intracellular particles. The present studies indicate duck red cells use this mechanism to readjust their total monovalent cation content and thus their solute content in isotonic media as well. In addition, evidence is presented which indicates that the "volume-controlling mechanism" and ouabain-inhibitable cation pump differ functionally.

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

“…K moves toward its electrochemical equilibrium. ' Thus, the mechanism responsible for the K loss and volume regulation seen here resembles that reported previously (1,3). This is illustrated further by the observation that introducing ouabain (10-4 M) to the bathing medium has little effect on the changes in cell size (Fig.…”

“…The findings presented in this paper and elsewhere (1,3) show that under unsteady-state conditions a membrane pathway, C, becomes apparent in duck erythrocytes. It is through this pathway that the volume controlling mechanism, designated D, controls K loss from enlarged cells.…”

Volume-regulatory responses of Amphiuma red cells in anisotonic media. The effect of amiloride.

“…Previous reports in avian red cells indicated that catecholamines stimulate a cAMPdependent transport mechanism similar to that of the avian VRI response (Riddick et al, 1971 ;Kregenow, 1973;Kregenow et al, 1976). The possibility that hypertonicity and catecholamine-stimulated salt transport in avian and amphibian red cells may have common characteristics was anticipated by the work of Orskov (1954Orskov ( , 1956a.…”

Physiology of Cell Volume Regulation in Vertebrates

“…B) NKCC1 AS A MECHANISM OF RVI. Coupled anion-cation transport in RVI was first demonstrated in avian RBCs (475,476) and shortly after in mammalian cells (32, 355). Similar to NHE1, NKCC1 is a major mediator of RVI in a wide variety of cell types studied.…”