Two types of K+ channel in thick ascending limb of rat kidney

Wen Hui Wang

Research output: Contribution to journalArticlepeer-review

52 Scopus citations


We have used the patch-clamp technique to study the apical K+ channels in the thick ascending limb (TAL) of the rat kidney. Two types of K+ channels, a low-conductance and an intermediate-conductance K+ channel, were identified in both cell-attached and inside-out patches. We confirmed the previously reported intermediate-conductance K+ channel (72 pS), which is inhibited by millimolar cell ATP, acidic pH, Ba2+, and quinidine (4). We now report a second K+ channel in apical membrane of the TAL. The slope conductance of this low-conductance K+ channel is 30 pS, and its open probability is 0.80 in cell-attached patches. This channel is not voltage dependent, and application of 2 mM ATP in the bath inhibits channel activity in inside-out patches. In addition, 250 μM glyburide, an ATP-sensitive K+ channel inhibitor, blocks channel activity, whereas the same concentration of glyburide has no inhibitory effect on the 72-pS K+ channel. Channel activity of the 30-pS K+ channel decreases rapidly upon excision of patches (channel run down). Application of 0.1 mM ATP and the catalytic subunit of adenosine 3′,5′-cyclic monophosphate (cAMP)-dependent protein kinase A (PKA) restores channel activity. Furthermore, addition of 0.1 mM 8-(4-chlorophenylthio)-cAMP or 50-100 pM vasopressin in the cell-attached patches increases channel activity. In conclusion, two types of K+ channels are present in the apical membrane of TAL of rat kidney, and PKA plays an important role in modulation of the low-conductance K+ channel activity.

Original languageEnglish
Pages (from-to)F599-F605
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Issue number4 36-4
StatePublished - Oct 1994
Externally publishedYes


  • Adenosine 3′,5′-cyclic monophosphate
  • Adenosine triphosphate-sensitive potassium channel
  • Glyburide
  • Protein kinase A
  • Vasopressin


Dive into the research topics of 'Two types of K+ channel in thick ascending limb of rat kidney'. Together they form a unique fingerprint.

Cite this