title: Direct evidence for histamine H3 receptor-mediated inhibition of norepinephrine release from sympathetic terminals of guinea pig myocardium.
abstract: OBJECTIVE
  To study the histamine H3 receptors mediated inhibition of norepinephrine (NE) release from cardiac sympathetic terminals of guinea pig isolated atria.
  
  
  METHODS
  Release of NE induced by electric field stimulation (50 mA, 5 ms) in the bath solution was measured by HPLC-ECD.
  
  
  RESULTS
  The release of NE caused by field stimulation was attenuated by (R)-alpha-methyl-histamine (alpha-MeHA, 0.1 nmol.L-1(-10) mumol.L-1) in a concentration-dependent manner. Thioperamide concentration-dependently antagonized the inhibition of alpha-MeHA. Blockade of H1, H2, alpha 2, beta 2-receptors failed to prevent the inhibitory effect of alpha-MeHA. Thioperamide (1 nmol.L-1(-10) mumol.L-1), when used alone, concentration-dependently facilitated the release of NE evoked by field stimulation.
  
  
  CONCLUSIONS
  The presynaptic histamine H3-receptors inhibited the NE release from cardiac sympathetic terminals.
authors.affiliation: Department of Pharmacology, Xijing Hospital, Fourth Military Medical University, Xi-an, China.
authors.forename: X X
authors.initials: XX
authors.lastname: Luo
authors.forename: A D
authors.initials: AD
authors.lastname: Wen
authors.forename: Z A
authors.initials: ZA
authors.lastname: Guo
authors.forename: Y H
authors.initials: YH
authors.lastname: Tan
mesh_terms: D000320:Adrenergic Fibers / Q000378:metabolism; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D006168:Guinea Pigs; D006325:Heart Atria / Q000294:innervation / Q000378:metabolism; D017442:Histamine Agonists / Q000494:pharmacology*; D006633:Histamine Antagonists / Q000494:pharmacology; D008297:Male; D008761:Methylhistamines / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism*; D010880:Piperidines / Q000494:pharmacology; D018100:Receptors, Histamine H3 / Q000502:physiology; D013564:Sympathetic Nervous System / Q000378:metabolism
chemical_list: D017442:Histamine Agonists; D006633:Histamine Antagonists; D008761:Methylhistamines; D010880:Piperidines; D018100:Receptors, Histamine H3; C069357:alpha-methylhistamine; C052075:thioperamide; D009638:Norepinephrine