title: Effects of calcium antagonists and agonists on isolated human v. saphena magna used for coronary artery bypass grafting and guinea pig's papillary muscle.
abstract: BACKGROUND
  The goal of this study was to investigate the movement of contraction-relaxation effects on isolated human blood vessel samples by the actions of amlodipine (CAS 88150-42-9), cerebrocrast (CAS 118790-71-9), diltiazem (CAS 42399-41-7), and a benzimidazole derivative. Additionally, their effects on isometric contraction force and the duration of the action potential (AP) were measured.
  
  
  METHODS
  The experiments were carried out on isolated human v. saphena magna samples and papillary muscles of adult guinea pigs. Isometric contraction and the AP were recorded using a force transducer and standard microelectrode technique.
  
  
  RESULTS
  Phenylephrine (10(-4) M) caused contractions of vein rings to 928 +/- 76.5 mg. All the tested agents at a concentration of 10(-7)-10(-4) M significantly relaxed the smooth muscle in a dose-dependent manner. The weakest response was shown by amlodipine. Pre-treatment with 50 microM of amlodipine, diltiazem and benzimidazole for 30 min significantly increased the magnitude of the contraction induced by phenylephrine in concentration-dependent (10(-6)-10(-4) M) fashion but only in the benzimidazole group versus other tested agents and the control. The benzimidazole derivative caused augmentation of isometric contraction of the papillary muscles and negligible lengthening of AP duration; the other agents tested showed opposite effects.
  
  
  CONCLUSIONS
  These results show that agents possessing positive or negative inotropic action significantly relaxed the isolated vein samples precontracted with phenylephrine. These responses point to a different mechanism of action underlying both calcium antagonist and agonist effects even though their action ultimately resulted in vasodilatation.
authors: Institute of Cardiology at Medical Academy of Lithuanian University of Health Sciences, Kaunas, Lithuania. vida.garaliene@gmail.com
authors: Vida
authors: V
authors: Garaliene
authors: Vygantas
authors: V
authors: Barsys
authors: Povilas
authors: P
authors: Jakuska
authors: Aivars
authors: A
authors: Krauze
authors: Gunar
authors: G
authors: Duburs
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017311:Amlodipine / Q000494:pharmacology; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology; D002120:Calcium Channel Agonists / Q000494:pharmacology*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D001026:Coronary Artery Bypass; D004095:Dihydropyridines / Q000494:pharmacology; D004110:Diltiazem / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D010210:Papillary Muscles / Q000187:drug effects; D010656:Phenylephrine / Q000494:pharmacology; D012501:Saphenous Vein / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D001562:Benzimidazoles; D002120:Calcium Channel Agonists; D002121:Calcium Channel Blockers; D004095:Dihydropyridines; D014662:Vasoconstrictor Agents; C073838:2,6-dimethyl-3,5-bis(2'-propoxyethoxycarbonyl)-4-(2''-difluoromethoxyphenyl)-1,4-dihydropyridine; D017311:Amlodipine; D010656:Phenylephrine; D004110:Diltiazem