Dog red blood cells: Na and K diffusion potentials with extracellular ATP.

Abstract

n B S T R A C T External ATP causes a prompt increase in the Na and K permeability of dog red blood cells. By manipulating intra-and extracellular ion composition it is possible to observe ATP-induced net fluxes which can be explained in terms of the contribution of Na or K diffusion potentials to the membrane potential. Measurements of membrane voltage by a fluorescent dye technique confirm the existence of such potentials. A rough calculation of chloride permeability gives a value of the order of 10 -s cm/s, which agrees with results in other species. The cells appear to be somewhat more permeable to bromide than to chloride. I N T R O D U C T I O NAn interesting p r o p e r t y of dog red blood cells is that their permeability to Na and K increases on exposure to external A T P in concentrations of 0.1-1.0 mM (Parker and Snow, 1972;Elford, 1975;Romualdez et al., 1976). T h e effect is A T P specific and reversible. It can be p r e v e n t e d by including physiologic concentrations o f divalent cations in the m e d i u m and is t h e r e f o r e of uncertain significance for the cell's function in vivo. This action of exogenous A T P was first described in ascites t u m o r cells ( H e m p l i n g et Stewart et al., 1969) and has also been r e p o r t e d in isolated renal tubules (Rorive and Kleinzeller, 1972) and other tissues ( T r a m s , 1974). T h e mechanism of A T P ' s interaction with the m e m b r a n e surface is obscure.We suspected that in the presence of external A T P dog red cells might b e c o m e as p e r m e a b l e to Na and K as they are to small anions. O u r hypothesis was c o n f i r m e d by m e a s u r e m e n t s o f net ion flux and m e m b r a n e potentials. T h e data have f u r t h e r m o r e allowed us to draw some conclusions about chloride and b r o m i d e m o v e m e n t s in this species o f cell. This a p p r o a c h has p r e c e d e n t in work with cation-specific i o n o p h o r e s such as gramicidin and valinomycin (Scarpa et al., 1968; H u n t e r , 1971;Tosteson et al., 1973).It should be emphasized that the data in the present study concern net anion movements, presumably by electrodiffusion. Dog red blood cells have a tightly coupled, electrically silent anion exchange mechanism similar to that of all other species examined (Wieth et al., 1974). T h e possible relationship between net and exchange pathways will be briefly discussed in connection with o u r observations on the m o v e m e n t s o f different halide ions.

Changes in Red Blood Cell Electrolytes and ATP in Newborn Shock

“…Calcium and magnesium concentrations were measured. Preliminary studies in our laboratory confirm previous reports that the procedures used in cell washing, incubation, and centrifugation did not alter water or electrolyte content of the red blood cells (16,17,19,20). The electrolyte content in packed red blood cells was expressed as mM/liter cell water.…”

“…, ' In conducting the research the investigators adhered to the National Institutes 14,19). The remaining aliquot of red blood cells was washed of Health and American Physiological Society guidelines for use of experimental twice with isotonic media (5" C ) and recentrifuged as described animals.…”

Effects of amrinone, a cardiotonic drug, on calcium movements in dog erythrocytes.

“…Alteration of cell Na and K content by incubation with extracellular ATP is described in the legend to Fig. 6 aind in more detail in previous reports (10,11).…”

“…Dog RBC have an internal Na concentration of 150 mmol/kg cell water-virtually the same as that of plasma; the membrane potential of -8 to -10 mV constitutes a driving force for Na entry (11,13). Despite their lack of a K-or digitalis-sensitive Na efflux, and although they have no Na,K-ATPase, dog RBC can pump Na outward provided Ca is present in the medium (6).…”

Effect of Endogenous and Exogenous Adenosine-Three Phosphate on Erythrocyte Deformability

“…Akd Tıp D / Akd Med J / 2017; 1: [29][30][31][32][33][34] süspansiyonlarına dışarıdan eklenecek eksojen ve mekanik stres uygulamasıyla hücreden çıkışı uyarılacak olan endojen ATP'nin eritrosit deformabilitesine etkilerini incelemektir.…”