Cation channels of the rabbit outer medullary collecting duct.
The outer medullary collecting duct (OMCD) produces high rates of proton secretion, and previous data show a significant role for an H+,K+-ATPase in luminal acidification. This mechanism of acidification requires proton secretion to occur in exchange for potassium absorption. Because net transport of potassium is small in the OMCD, pathways for potassium secretion would appear essential to explain the contribution of an H+,K+-ATPase under potassium-replete conditions. A significant issue is whether a potassium exit pathway (i.e., cation channel) is present at the apical and/or the basolateral membrane. In this report, using patch-clamp techniques to examine single channel conductances from the native rabbit OMCD, we show that the apical membrane has potassium permeable cation channels.
Xia
S L
SL
Department of Physiology, The University of Florida, 32610-0224, USA. xiasl@vahmed.ufl.edu
Gelband
C H
CH
Wingo
C S
CS
D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D017506:H(+)-K(+)-Exchanging ATPase / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology; D017136:Ion Transport / Q000502:physiology; D007679:Kidney Medulla; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism*; D017494:Proton Pumps / Q000502:physiology; D011817:Rabbits; D012680:Sensitivity and Specificity
D017494:Proton Pumps; D017506:H(+)-K(+)-Exchanging ATPase; D011188:Potassium