AQP4 role in renal K+ transport
2009 (English)In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 23, 867.2- p.Article in journal, Meeting abstract (Other academic) Published
The collecting duct principle cells (PC) play a major role for concentration of urine and regulation of K+ homeostasis. Two water channels, AQP3 and AQP4, are expressed in the PC basolateral membrane (BLM). Here we present evidence that AQP4 participates in regulation of renal K+ transport. K+ enters the cell via Na+,K+-ATPase mediated transport in BLM. The presence of K+ channels in BLM, which is deeply infolded, thus providing a diffusion limited space, permits K+ recirculation, considered important for maintenance of membrane potential. Here we show with co-immunoprecipitation and GST pulldown assays, that in rat renal papilla, AQP4, but not AQP3, assembles with Na+,K+-ATPase and the K+ channel Kir7.1. This led us to hypothesize that AQP4, Na+,K+-ATPase and Kir7.1 form a K+ transporting microdomain, where AQP4 water transport maintains a favorable gradient for K+ efflux and stabilizes membrane potential. A mathematical model of K+ transport across an epithelial cells with a deeply infolded BLM supported the hypothesis and predicted an even higher impact of AQP water transport on K+ transport if AQP water permeability is sensitive to fluctuations in extracellular K+ concentration ([K+]o). To test this, AQP3 and AQP4 were expressed in MDCK cells, a cell line with much in common with PC. Water permeability was increased when [K+]o was 12mM in cells expressing AQP4 but not in cells expressing AQP3.
Place, publisher, year, edition, pages
American Societies for Experimental Biology , 2009. Vol. 23, 867.2- p.
Biochemistry and Molecular Biology
IdentifiersURN: urn:nbn:se:kth:diva-138116ISI: 000208621502239OAI: oai:DiVA.org:kth-138116DiVA: diva2:680567
QC 20131218. QC 201602092013-12-182013-12-182016-02-09Bibliographically approved