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Histamine responses mediated via H1- and H2-receptors in the isolated portal vein of the dog.

Authors
  • Toshimitsu, Y
  • Uchida, K
  • Kojima, S
  • Shimo, Y
Type
Published Article
Journal
The Journal of pharmacy and pharmacology
Publication Date
Jun 01, 1984
Volume
36
Issue
6
Pages
404–405
Identifiers
PMID: 6146675
Source
Medline
License
Unknown

Abstract

The effects of histamine were studied on the isolated circular muscle strip and longitudinal muscle strip of the dog portal vein. Histamine-induced contractions of the circular muscle were inhibited by H1-receptor antagonist pyrilamine but increased by H2-receptor antagonist ranitidine. When the tissues were contracted with PGF2 alpha in the presence of pyrilamine, histamine produced the relaxation of the circular muscle but not longitudinal muscle. The relaxation of the circular muscle was inhibited by ranitidine in a concentration dependent manner, the pA2 value for ranitidine being 6.97 (6.55-7.39). It is concluded that the response of the circular muscle to histamine is the sum of two components, H1-receptor mediated contraction and H2-receptor mediated relaxation.

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