Original ArticleThe Effects of Potassium Channel Opener P1075 on the Human Saphenous Vein and Human Internal Mammary ArteryGojkovic-Bukarica, Ljiljana C PhD*; Beleslin-Cokic, Bojana B MD*; Novakovic, Aleksandra N PhD†; Peric, Miodrag S PhD‡; Markovic-Lipkovski, Jasmina Z PhD§; Cirovic, Sanja Z BSc§; Nezic, Dusan G PhD‡; Lesic, Aleksandar R PhD§; Kanjuh, Vladimir I PhD¶; Heinle, Helmut PhD‖Author Information From the *Department of Clinical Pharmacology, Pharmacology and Toxicology, Faculty of Medicine, University Belgrade, Belgrade, Serbia; †Department of Pharmacology, Faculty of Pharmacy, University Belgrade, Belgrade, Serbia; ‡Institute for Cardiovascular Diseases “Dedinje,” University Belgrade, Belgrade, Serbia; §Institute of Pathology, Medical Faculty, University Belgrade, Belgrade, Serbia; ¶Serbian Academy of Sciences and Arts, Belgrade, Serbia; and ‖Institute of Physiology, University Tübingen, Germany. Received for publication December 16, 2010; accepted February 6, 2011. L. Gojkovic-Bukarica was supported by Scientific Research Grants from the Ministry of Science and Technology 31020 and 175047 (Serbia), the Karl & Lora Klein Foundation, and the Alexander von Humboldt Foundation (Germany). The authors declare no conflicts of interest. Reprints: Ljiljana C. Gojkovic-Bukarica, PhD, Department of Clinical Pharmacology, Pharmacology and Toxicology, P.O. Box 38, Dr Subotica 1, Belgrade 11129, Serbia (e-mail: firstname.lastname@example.org). Journal of Cardiovascular Pharmacology: June 2011 - Volume 57 - Issue 6 - p 648-655 doi: 10.1097/FJC.0b013e3182145850 Buy Metrics Abstract Because adrenergic contractions can contribute to the development of life-threatening spasm of coronary artery bypass graft, this study was performed to investigate the effect of adenosine 3-phosphate (ATP)-sensitive K+ channel (KATP) opener P1075 on contractions of isolated human saphenous vein (HSV) and human internal mammary artery (HIMA). Phasic contractions were evoked by electric field stimulation (20 Hz) and noradrenaline. The sustained contractions were evoked by phenylephrine. The presence of pore-forming Kir6.1 and Kir6.2 subunits of the KATP channels in the HIMA and only Kir6.2 in the HSV was confirmed immunomorphologically. P1075 inhibited in the HSV only, the electrical field stimulation contractions more strongly than noradrenaline contractions. In addition, the phenylephrine contractions of HSV were more sensitive to P1075 in comparison to those of HIMA. Glibenclamide, a KATP channel blocker antagonized the vasodilatation produced by P1075 in both grafts differently, because its effect was more prominent on the P1075-induced inhibition of contractions of HSV than of HIMA. We conclude that P1075 has a vasorelaxant effect and inhibited adrenergic contractions of the tested grafts. This effect is graft and vasoconstrictor selective and seems to be mediated by Kir6.1- and/or Kir6.2-containing KATP channels. Thus, P1075 can be considered as a potential drug in the prevention of graft spasm. © 2011 Lippincott Williams & Wilkins, Inc.