title: Role of nicotinic acetylcholine receptor subtypes on nicotine's enhancing effect on electrical field stimulation elicited contractile responses in rabbit urine bladder.
abstract: This study aims to investigate the contribution of presynaptic nicotinic acetylcholine receptors (nAChRs) sub-types to nicotine-induced enhancement in electrical field stimulation (EFS) EFS-mediated contractile responses in rabbit urine bladder smooth muscle preparations.
  
  
  
  Rabbit urine bladder smooth muscle strips were placed in organ baths containing 20 ml of an aerated Krebs-Henseleit solution, and contractions were recorded using isometric force displacement transducers. Following the acquisition of control EFS (60 V, 8 Hz, 1 ms) responses, nicotine was added to the bath at a 3×10-5 M concentration, and EFS responses were obtained. The effect of nAChR antagonists on nicotine-induced augmentation in EFS-mediated responses was investigated in the presence of hexamethonium, dihydro-β-erythroidine, mecamylamine, and α-bungarotoxin.
  
  
  
  Tetrodotoxin (TTX; 10-6 M) completely blocked EFS-induced contractile responses in smooth muscle strips. Similarly, Atropine (10-6 M), when administered with α,β-methylene adenosine triphosphate (α,β-methylene-ATP) (10-5 M), completely blocked EFS responses. Nicotine significantly enhanced EFS-mediated contractile responses (23.67% ± 1.75). Nicotine-induced increases in EFS responses were largely inhibited by hexamethonium, mecamylamine, and dihydro-β-erythroidine, whereas α-bungarotoxin only partly inhibited these enhancements.
  
  
  
  These findings demonstrate that EFS-induced neurogenic contractions in rabbit urine bladder smooth muscle strips are mediated by purinergic and cholinergic transmissions, and the α4β2, α3β4, and α7 sub-types of nAChRs contribute to the enhancement effect of nicotine on EFS-induced contractile responses.
authors.affiliation: Department of Medical Pharmacology, Faculty of Medicine, Gazi University, Ankara, Turkey. gokcesevimozturk@yahoo.com.
authors.forename: G S
authors.initials: GS
authors.lastname: Ozturk Fincan
authors.forename: I M
authors.initials: IM
authors.lastname: Vural
authors.forename: S S
authors.initials: SS
authors.lastname: Yildirim
authors.forename: F
authors.initials: F
authors.lastname: Isli
authors.forename: E
authors.initials: E
authors.lastname: Dilekoz
authors.forename: S
authors.initials: S
authors.lastname: Ercan
authors.forename: Y
authors.initials: Y
authors.lastname: Sarioglu
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009538:Nicotine / Q000494:pharmacology*; D011817:Rabbits; D011978:Receptors, Nicotinic; D001743:Urinary Bladder / Q000187:drug effects
chemical_list: D011978:Receptors, Nicotinic; D009538:Nicotine