title: Calcium channel antagonists and inhibition of human sphincter of Oddi contractions.
abstract: OBJECTIVE
  Nifedipine has been used in the treatment of sphincter of Oddi dyskinesia, a biliary disease characterized by upper abdominal pains and increased pressure in the sphincter. The effects of other calcium channel antagonists on sphincter of Oddi have not been elucidated.
  
  
  METHODS
  We compared the effects of three calcium blockers with differing smooth muscle selectivity (verapamil, nifedipine and felodipine) on human sphincter of Oddi contractions. Transverse sections of the sphincter obtained from five patients undergoing Whipple resection were studied in an organ bath chamber in vitro.
  
  
  RESULTS
  All three calcium blockers significantly (>50%) inhibited the acetylcholine-induced and KCl-induced sphincter contractions in a dose-dependent manner. Both nifedipine and felodipine were more potent than verapamil in inhibiting the acetylcholine-induced contractions, whereas only nifedipine, but not felodipine, reduced the KCl-elicited contractions more than verapamil.
  
  
  CONCLUSIONS
  The smooth muscle selective calcium channel antagonists are potent inhibitors of human sphincter of Oddi contractions. Although nifedipine is, to date, the only agent studied in clinical settings, other dihydropyridines are also likely to be useful in sphincter of Oddi dyskinesia.
authors.affiliation: Department of Gastroenterology and Alimentary Tract Surgery, Tampere, Finland. juhani.sand@pshp.fi
authors.forename: Juhani
authors.initials: J
authors.lastname: Sand
authors.forename: Pertti
authors.initials: P
authors.lastname: Arvola
authors.forename: Isto
authors.initials: I
authors.lastname: Nordback
mesh_terms: D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015736:Felodipine / Q000494:pharmacology*; D006801:Humans; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000503:physiopathology; D009543:Nifedipine / Q000494:pharmacology*; D009803:Sphincter of Oddi / Q000187:drug effects* / Q000503:physiopathology; D013268:Stimulation, Chemical; D046509:Tissue Culture Techniques; D014700:Verapamil / Q000494:pharmacology*
chemical_list: D002121:Calcium Channel Blockers; D014700:Verapamil; D009543:Nifedipine; D015736:Felodipine