INFLUENCE OF A LOW-POTASSIUM DIET ON RAT-ERYTHROCYTE-MEMBRANE ADENOSINE TRIPHOSPHATASE

Wistar rats were provided a low-potassium dietary regimen for varying time intervals up to 10 weeks. Within 2 weeks plasma potassium concentration was reduced; from the fifth to the tenth week it remained at about half the value for normal plasma. Starting at the fifth week of the low-potassium dietary regimen, the (Na + K)-dependent ATPase in the erythrocyte membrane of the potassium-depleted rats showed a steady increase in specific activity; by the tenth week, it was 50-100% higher than that of control rats. On the other hand, there were no detectable changes in another stromal enzyme, acetylcholine esterase, in the membrane preparations of potassium-depleted rats. In subsequent experiments low-potassium rats (depleted for 10 weeks) were returned to a complete diet for varying intervals. Plasma potassium concentration became normal within 1 week. But (Na + K)-dependent ATPase in the erythrocyte membrane decreased slowly and reached a normal level only after about 5 weeks on the complete diet. The results suggest that the decrease in the plasma potassium concentration results in an induction of the erythrocyte membrane (Na + K)-dependent ATPase. © 1969.