title: Distinct and complementary roles for α and β isoenzymes of PKC in mediating vasoconstrictor responses to acutely elevated glucose.
abstract: OBJECTIVE
  We investigated the hypothesis that elevated glucose increases contractile responses in vascular smooth muscle and that this enhanced constriction occurs due to the glucose-induced PKC-dependent inhibition of voltage-gated potassium channels.
  
  
  METHODS
  Patch-clamp electrophysiology in rat isolated mesenteric arterial myocytes was performed to investigate the glucose-induced inhibition of voltage-gated potassium (Kv ) current. To determine the effects of glucose in whole vessel, wire myography was performed in rat mesenteric, porcine coronary and human internal mammary arteries.
  
  
  RESULTS
  Glucose-induced inhibition of Kv was PKC-dependent and could be pharmacologically dissected using PKC isoenzyme-specific inhibitors to reveal a PKCβ-dependent component of Kv inhibition dominating between 0 and 10 mM glucose with an additional PKCα-dependent component becoming evident at concentrations greater than 10 mM. These findings were supported using wire myography in all artery types used, where contractile responses to vessel depolarization and vasoconstrictors were enhanced by increasing bathing glucose concentration, again with evidence for distinct and complementary PKCα/PKCβ-mediated components.
  
  
  CONCLUSIONS
  Our results provide compelling evidence that glucose-induced PKCα/PKCβ-mediated inhibition of Kv current in vascular smooth muscle causes an enhanced constrictor response. Inhibition of Kv current causes a significant depolarization of vascular myocytes leading to marked vasoconstriction. The PKC dependence of this enhanced constrictor response may present a potential therapeutic target for improving microvascular perfusion following percutaneous coronary intervention after myocardial infarction in hyperglycaemic patients.
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Jackson
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK.
authors.forename: Sean
authors.initials: S
authors.lastname: Brennan
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Fielding
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK.
authors.forename: Mark W
authors.initials: MW
authors.lastname: Sims
authors.affiliation: Department of Molecular and Cell Biology, University of Leicester, Leicester, UK.
authors.forename: R A John
authors.initials: RA
authors.lastname: Challiss
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK.
authors.forename: David
authors.initials: D
authors.lastname: Adlam
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK.
authors.forename: Iain B
authors.initials: IB
authors.lastname: Squire
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, Glenfield General Hospital, Leicester, UK.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Rainbow
mesh_terms: D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000502:physiology; D008297:Male; D008323:Mammary Arteries / Q000187:drug effects* / Q000502:physiology; D008638:Mesenteric Arteries / Q000187:drug effects* / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000502:physiology; D024642:Potassium Channels, Voltage-Gated / Q000502:physiology; D064546:Protein Kinase C beta / Q000037:antagonists & inhibitors / Q000502:physiology*; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000502:physiology*; D017208:Rats, Wistar; D013552:Swine; D014661:Vasoconstriction / Q000187:drug effects
chemical_list: D007527:Isoenzymes; D024642:Potassium Channels, Voltage-Gated; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha; D005947:Glucose