Reduced ion transport in erythrocytes of male Sprague-Dawley rats during starvation.
Although several studies have suggested that the reduced activity of the Na+-K+ pump during starvation is a source of energy conservation, the hypothesis has not been tested in intact cells, nor has the contribution of passive permeability been considered in a controlled animal study. In this study three components of K+ influx (Na+-K+ pump = ouabain sensitive, cotransport = bumetanide sensitive and leak = both ouabain and bumetanide insensitive) and Na+ influx were measured with 42K+ and 24Na+ in intact red blood cells of adult male rats. During starvation rats lost an average of 28% of their body weight; pump K+ influx in cells stabilized for 2 h in incubation medium fell from 7.03 +/- 0.74 (SEM) to 4.82 +/- 0.25 mueq/(mL cells.h) with cell [Na+] of 6.4 +/- 0.9 and 4.4 +/- 0.2 mmol/L cells, respectively. Maximized Na+-K+ pump activity in Na+-loaded cells was also lower in cells of starved rats than in those of controls and was inversely correlated with extent of weight loss in the starved rats. Leak K+ influx was reduced from 0.73 +/- 0.08 to 0.47 +/- 0.03. Lower Na+ influx in cells of starved rats was not significant statistically, although alteration in passive Na+ transport was apparent. The results indicate decreases in both active and passive components of ion turnover of erythrocytes of rats during starvation.
Department of Physiology and Biophysics, University of Illinois, Urbana 61801.
M J
MJ
Zhao
J S
JS
Willis
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001693:Biological Transport, Active / Q000187:drug effects; D002034:Bumetanide / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000097:blood*; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000097:blood*; D013217:Starvation / Q000097:blood*
D002034:Bumetanide; D010042:Ouabain; D012964:Sodium; D011188:Potassium