Regulation of renal Na+,K(+)-ATPase in rat thick ascending limb during K+ depletion: evidence for modulation of Na+ affinity.

摘要: 1. NaCl reabsorption along the loop of Henle is reduced in K(+)-depleted rats. Because Na+,K(+)-ATPase energizes this transport and because K+ depletion known to induce an upregulation most tissues, regulation enzyme was investigated at level single thick ascending limbs freshly microdissected from rats fed either a normal (control rats) or low-K+ diet (LK rats). 2. Within 2 weeks depletion, activity [3H]ouabain binding were increased by 30-50% medullary portion limb (MTAL). 3. Despite increase number units, capacity Na+,K+ pump, determined ouabain-sensitive Rb+ uptake presence extracellular concentration mimicking kalaemia control (4.0 mM Rb+) LK (2.3 Rb+), MTAL 4. Inhibition pump not accounted for changes intracellular Na+ concentrations, but decrease affinity Na+. 5. change apparent detectable intact permeabilized cells, it probably induced rapidly reversible cytosolic factor.