Difference in the Na affinity of Na(+)-K(+)-ATPase along the rabbit nephron: modulation by K.

摘要: The sensitivity of Na(+)-K(+)-ATPase to Na was determined in single segments rabbit nephron isolated by microdissection. In the cortical collecting tubule (CCT), threefold more sensitive (apparent K0.5 approximately 3 mM) than proximal convoluted and thick ascending limb 10 mM). Furthermore, increasing K concentration from 5 greater 100 mM markedly reduced affinity pump for all three segments. fact, main shift occurred when changed 120 mM; CCT, while maintaining at activity 35%. These findings confirm that, kidney cells as other cells, intracellular limits rate Na(+)-K(+)-ATPase. Thus any alteration modifies a way that contributes restoration homeostasis. This adaptive property is particularly efficient which apparent close normal concentration. changes concentration, usually accompany those so maintain total cation constant, potentiate regulatory role through modifications its pump.