Afferent arteriolar dilation to 11, 12-EET analogs involves PP2A activity and Ca2+-activated K+ Channels

Microcirculation. 2008 Feb;15(2):137-50. doi: 10.1080/10739680701456960.

Abstract

The epoxygenase metabolite, 11, 12-epoxyeicosatrienoic acid (11, 12-EET), has renal vascular actions. 11, 12-EET analogs have been developed to determine the structure activity relationship for 11, 12-EET and as a tool to investigate signaling mechanisms responsible for afferent arteriolar dilation. We hypothesized that 11, 12-EET mediated afferent arteriolar dilation involves increased phosphoprotein phosphatase 2A (PP2A) and large-conductance calcium activated K+ (KCa) channels. We evaluated the chemically and/or metabolically table 11, 12-EET analogs: 11, 12-EET-N-methylsulfonimide (11, 12-EET-SI), 11-nonyloxy-undec-8(Z)-enoic acid (11, 12-ether-EET-8-ZE), and 11, 12-trans-oxidoeicosa-8(Z)-eonoic acid (11, 12-tetra-EET-8-ZE). Afferent arteriolar responses were assessed. Activation of KCa channels by 11, 12-EET analogs were established by single cell channel recordings in renal myocytes. Assessment of renal vascular responses revealed that 11, 12-EET analogs increased afferent arteriolar diameter. Vasodilator responses to 11, 12-EET analogs were abolished by K+ channel or PP2A inhibition. 11, 12-EET analogs activated renal myocyte large-conductance KCa channels. 11, 12-EET analogs increased cAMP by 2-fold and PP2A activity increased 3-8 fold in renal myocytes. PP2A inhibition did not significantly affect the 11, 12-EET analog mediated increase in cAMP and PP2A increased renal myocyte KCa channel activity to a much greater extent than PKA. These data support the concept that 11, 12-EET utilizes PP2A dependent pathways to activate large-conductance KCa channels and dilate the afferent arteriole.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 8,11,14-Eicosatrienoic Acid / analogs & derivatives*
  • 8,11,14-Eicosatrienoic Acid / pharmacology
  • Animals
  • Arterioles / metabolism
  • Cyclic AMP / metabolism
  • Kidney / blood supply*
  • Large-Conductance Calcium-Activated Potassium Channels / antagonists & inhibitors
  • Large-Conductance Calcium-Activated Potassium Channels / metabolism*
  • Male
  • Muscle Cells / metabolism
  • Oxidoreductases / metabolism
  • Protein Phosphatase 2 / antagonists & inhibitors
  • Protein Phosphatase 2 / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Structure-Activity Relationship
  • Vasodilation / drug effects*
  • Vasodilator Agents / pharmacology*

Substances

  • Large-Conductance Calcium-Activated Potassium Channels
  • Vasodilator Agents
  • 11,12-epoxy-5,8,14-eicosatrienoic acid
  • Cyclic AMP
  • Oxidoreductases
  • Ppp2ca protein, rat
  • Protein Phosphatase 2
  • 8,11,14-Eicosatrienoic Acid