Effect of cold acclimation on Na+/K+ transport in hamster liver cells

Summary The effects of prolonged cold exposure of Syrian hamsters on liver membrane (Na⁺/K⁺-ATPase activity and on liver intracellular K⁺ levels was examined. Membrane preparations from cold-acclimated hamsters (6°C for 3 weeks) exhibited significantly higherV_max values for (Na⁺/K⁺)-ATPase and significantly greater ouabain binding. These data support the view that in the liver of these cold-exposed hamsters, there is an increase in the number of operational pumps. The fact that the intact liver cells (isolated via liver perfusion) from the cold-acclimated hamsters: (a) did not have higher concentrations of intracellular K⁺ (despite the presence of more operational pumps); and (b) exhibited greater rates of K⁺ loss when the pumps were inhibited by maximal ouabain suggests that the K⁺ leak across the liver cell plasma membrane is increased in the cold-acclimated hamsters. Although the physiological significance of these results needs further evaluation, these membrane changes may be of adaptive value for hibernation.Abbreviations CA cold-acclimated - P_i inorganic phosphate - KRB Krebs-Ringer-bicarbonate buffer - BSA bovine serum albumin - ECF extracellular fluid - ICF intracellular fluid - dcs dry cell solid - N nitrogen