K depletion leads to an increase in functional Na,K-ATPase activity in kidney homogen at es, microdissected medullary collecting tubules and cultured renal cells. This increase would be maladaptive in terms of renal K conservation unless if the increase in enzyme activity reflected, at least in part, sorting to the apical as opposed to the basolateral membrane. We have shown, by immunohistochemistry, that there is apical expression of Na,K-ATPase dl subunit in renal collecting tubules from rats with K depletion ( J Invest Med 1995;43:353A). The present study was undertaken to characterize Na,K-ATPase subunits expression during chronic K depletion. Rats were sacrificed after being fed a low potassium diet for 4-6 weeks ( plasma K 2. 6±0. 18 vs 4. 1+0. 13 mEq/L in pair fed controls P<0. 05). The relative abundance of Na,K-ATPase 81 and βl subunits was examined by immunoblotting of crude membrane preparations taken from renal cortex and medulla. Same amount of protein was loaded and resolved by SDS-PAGE, blotted and probed with subunits-specific d 1 and B l antibodies. The results (mean ±se) obtained by densitometry of the immunoblots were: dLsjibunit SI subunit Cortex Medulla Cortex Medulla Control 1. 28±0. 08 1. 33±0. 11 1. 0310. 17 0. 6110. 04 Low K 1. 8110. 10 1. 8610,16 2. 08±0. 27 1. 8810. 38 P value < 0. 025 < 0. 025 < 0. 005 < 0. 005 Conclusion: Plasma membrane protein abundance of both 81 and βl subunits of Na,K-ATPase is increased markedly in kidney cortex and medulla during K depletion. Taken together with our immunostaining data, the increment in plasma membrane Na. K-ATPase protein during K depletion likely reflects, at least in part, distribution to the apical membrane where it may subserve a role in K reabsorption rather than secretion.
|Original language||English (US)|
|Journal||Journal of Investigative Medicine|
|State||Published - Jan 1 1996|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)