title: The Effects of Potassium Channels in Human Internal Mammary Artery.
abstract: BACKGROUND
  Structural and functional changes in potassium channels of vascular smooth muscle cells may contribute to the development of diseases such as hypertension. We aim to investigate the vascular effects of potassium channel openers and blockers in human internal mammary artery (HIMA).
  
  
  METHODS
  Remaining segments of HIMA from 18 consecutive patients undergoing coronary artery bypass surgery were obtained to examine the vascular effects of various potassium channel openers (staurosporine, hydrochlorothiazide and cromakalim) and potassium channel blockers (4-aminopyridin [4-AP], charybdotoxin [CTX] and glibenclamide [GLBC]).
  
  
  RESULTS
  Noradrenaline (NA)-induced maximal contractions were inhibited by all 3 K+-channel blockers but only fully inhibited by 4-AP (95.6%). Only NA-induced contractions were reversed by CTX. Only K+-induced maximal contractions were significantly inhibited by 4-AP (95.6%, p < 0.05). Only acetylcholine-induced relaxation was fully inhibited by CTX. Only sodium nitroprusside-induced relaxations in potassium chloride-precontracted strips could be reversed by GLBC.
  
  
  CONCLUSIONS
  Drugs affecting potassium channels may be useful in the treatment of hypertension and management of perioperative vasospasm during the coronary artery bypass surgery.
authors.affiliation: Gynecologic Oncology Fellow, Gynecologic Oncology Division, Acx0131;badem University School of Medicine, Istanbul, Turkey.
authors.forename: Selim
authors.initials: S
authors.lastname: Afsar
authors.forename: Dogus
authors.initials: D
authors.lastname: Hemsinli
authors.forename: Sibel
authors.initials: S
authors.lastname: Ozyazgan
authors.forename: Ahmet Gökhan
authors.initials: AG
authors.lastname: Akkan
authors.forename: Caner
authors.initials: C
authors.lastname: Arslan
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D005260:Female; D006801:Humans; D054086:KATP Channels / Q000378:metabolism; D008297:Male; D008323:Mammary Arteries / Q000378:metabolism*; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D009126:Muscle Relaxation / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated / Q000378:metabolism
chemical_list: D054086:KATP Channels; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D024642:Potassium Channels, Voltage-Gated; D000109:Acetylcholine; D009638:Norepinephrine