Sejersted O M
Acta Physiol Scand. 1977 Mar;99(3):323-35. doi: 10.1111/j.1748-1716.1977.tb10385.x.
During saline infusion, sodium reabsorption (RNa) in the diluting segment (thick ascending limb of Henle's loop) increases acutely. The mechanism for this higher pumping rate of outer medullary Na-K-ATPase is unknown. Following left-sided nephrectomy, immediate i.v. infusion of hypertonic saline increased RNa in the remaining whole right kidney by 28 +/- 14% (p less than 0.05). Na-K-ATPase activity in outer medulla was raised by (delta) 23 +/- 4% above the left kidney (p less than 0.05), whereas cortical activity was unchanged. The mechanism for this increase in Na-K-ATPase activity was explored. The catalytic rate per enzyme did not differ in the two kidneys and equalled 5 340 min-1. The increase was therefore due to higher tissue concentration of active enzyme. The response was fully developed during continuous infusion within 20 min, and of equal magnitude whether protein synthesis had been inhibited by cycloheximide (delta = 23 +/- 7%) or stimulated by unilateral nephrectomy 6 days earlier combined with saline infusion for 2 h (delta = 34 +/- 10%). Thus, during hypertonic saline infusion, the increased RNa in the outer medulla was partly accounted for by the activation of latent Na-K-ATPase. High delivery of sodium to the diluting segment for more than 20 min during hypertrophy caused no further activity change.
在输注生理盐水期间，稀释段（亨氏袢升支粗段）的钠重吸收（RNa）会急剧增加。外髓质钠钾ATP酶这种较高泵浦速率的机制尚不清楚。左侧肾切除术后，立即静脉输注高渗盐水使剩余的整个右肾中的RNa增加了28±14%（p<0.05）。外髓质中的钠钾ATP酶活性比左肾升高了（δ）23±4%（p<0.05），而皮质活性未发生变化。对钠钾ATP酶活性增加的机制进行了探究。两种肾脏中每个酶的催化速率并无差异，均为5340分钟-1。因此，这种增加是由于活性酶的组织浓度较高所致。在持续输注20分钟内反应完全显现，无论蛋白质合成是被放线菌酮抑制（δ=23±7%）还是在6天前单侧肾切除并输注生理盐水2小时的情况下受到刺激（δ=34±10%），反应幅度均相同。因此，在输注高渗盐水期间，外髓质中RNa的增加部分是由潜在钠钾ATP酶的激活引起的。在肥大过程中，超过20分钟向稀释段大量输送钠并未导致活性进一步变化。
