title: Rosiglitazone inhibits vascular KATP channels and coronary vasodilation produced by isoprenaline.
abstract: OBJECTIVE
  Rosiglitazone is an anti-diabetic drug improving insulin sensitivity and glucose uptake in skeletal muscle and adipose tissues. However, several recent clinical trials suggest that rosiglitazone can increase the risk of cardiovascular ischaemia, although other studies failed to show such risks. Therefore, the effects of rosiglitazone on the coronary circulation and any potential vascular targets need to be elucidated. Here, we show that the vascular isoform of the ATP-sensitive K(+) (K(ATP) ) channel is inhibited by rosiglitazone, impairing physiological regulation of the coronary circulation.
  
  
  METHODS
  The K(IR) 6.1/SUR2B channel was expressed in HEK293 cells and studied in whole-cell and inside-out patch configurations. The Langendorff heart preparation was used to evaluate rosiglitazone in the coronary circulation of wild-type (WT) and K(IR) 6.1-null (Kcnj8(-/-) ) mice.
  
  
  RESULTS
  K(IR) 6.1/SUR2B channels in HEK cells were inhibited by rosiglitazone in a membrane-delimited manner. This effect was markedly enhanced by sub-micromolar concentrations of glibenclamide and the IC(50) for rosiglitazone fell to 2µM, a therapeutically achievable concentration. In the Langendorff heart preparation rosiglitazone inhibited, concentration-dependently, the coronary vasodilation induced by isoprenaline, without affecting basal coronary tone. Effects of rosiglitazone on coronary perfusion were attenuated by more than 50% in the Kcnj8(-/-) mice, supporting the involvement of K(ATP) channels in this effect of rosiglitazone on the coronary circulation.
  
  
  CONCLUSIONS
  These results indicate that the vascular K(ATP) channel is one of the targets of rosiglitazone action, through which this drug may compromise coronary responses to circulating vasodilators and perhaps also to metabolic stress.
authors.affiliation: Department of Biology, Georgia State University, Atlanta, GA 30302, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Yu
authors.forename: Xin
authors.initials: X
authors.lastname: Jin
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.forename: Ningren
authors.initials: N
authors.lastname: Cui
authors.forename: Chun
authors.initials: C
authors.lastname: Jiang
mesh_terms: D002460:Cell Line; D003331:Coronary Vessels / Q000187:drug effects*; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D000077154:Rosiglitazone; D045162:Thiazolidinediones / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D007004:Hypoglycemic Agents; D045162:Thiazolidinediones; D014665:Vasodilator Agents; D000077154:Rosiglitazone; D007545:Isoproterenol