Specific Binding of [3H]Pyrilamine to Histamine H1 Receptors in Guinea Pig Brain In Vivo: Determination of Binding Parameters by a Kinetic Four‐Compartment Model

Kazuhiko Yanai, Naoto Yagi, Takehiko Watanabe, Masatosi Itoh, Kiichi Ishiwata, Tatsuo Ido, Taiju Matsuzawa

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

The binding of [3H]pyrilamine, a selective ligand of histamine H1 receptors, to guinea pig brain in vivo was compared with its binding to a brain homogenate. The pharmacological properties (regional distribution, saturability, and stereoselectivity) of the [3H]pyrilamine binding in vivo were similar to those of the in vitro binding to brain homogenate. A dynamic four‐compartment model was proposed for the analysis of the kinetics of [3H]pyrilamine binding in vivo. The receptor constants in vivo were determined by a computer‐fitting method after correcting the radioactivity of arterial plasma and brain for the presence of radioactive metabolites. The in vivo association and dissociation were 213 and 42 times, respectively, slower than those of in vitro binding at 37°C. A possible mechanism for slow association and dissociation in vivo is discussed.

Original languageEnglish
Pages (from-to)409-420
Number of pages12
JournalJournal of Neurochemistry
Volume55
Issue number2
DOIs
Publication statusPublished - 1990 Aug

Keywords

  • Guinea pig brain.
  • Histamine H receptors
  • In vivo binding
  • Positron emission tomography
  • Pyrilamine
  • Tracer kinetics

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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