Activation of K+ channels in renal medullary vesicles by cAMP-dependent protein kinase

W. Brian Reeves, Glenn A. McDonald, Pramod Mehta, Thomas E. Andreoli

Research output: Contribution to journalArticle

38 Scopus citations

Abstract

ADH, acting through cAMP, increases the potassium conductance of apical membranes of mouse medullary thick ascending limbs of Henle. The present studies tested whether exposure of renal medullary apical membranes in vitro to the catalytic subunit of cAMP-dependent protein kinase resulted in an increase in potassium conductance. Apical membrane vesicles prepared from rabbit outer renal medulla demonstrated bumetanide-and chloride-sensitive22Na+ uptake and barium-sensitive, voltage-dependent86Rb+-influx. When vesicles were loaded with purified catalytic subunit of cAMP-dependent protein kinase (150 mU/ml), 1 mm ATP, and 50 mm KCl, the barium-sensitive86Rb+ influx increased from 361±138 to 528±120 pm/mg prot · 30 sec (P<0.01). This increase was inhibited completely when heat-stable protein kinase inhibitor (1 μg/ml) was also present in the vesicle solutions. The stimulation of86Rb+ uptake by protein kinase required ATP rather than ADP. It also required opening of the vesicles by hypotonic shock, presumably to allow the kinase free access to the cytoplasmic face of the membranes. We conclude that cAMP-dependent protein kinase-mediated phosphorylation of apical membranes from the renal medulla increases the potassium conductance of these membranes. This mechanism may account for the ADH-mediated increase in potassium conductance in the mouse mTALH.

Original languageEnglish (US)
Pages (from-to)65-72
Number of pages8
JournalThe Journal of Membrane Biology
Volume109
Issue number1
DOIs
StatePublished - Jul 1 1989
Externally publishedYes

Keywords

  • ADH
  • cAMP-dependent protein kinase
  • mTALH K channels

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Cell Biology

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