Characteristics of [3H]mepyramine binding in DDT1MF-2 cells: evidence for high affinity binding to a functional histamine H1 receptor

Eur J Pharmacol. 1994 Jul 15;268(2):257-62. doi: 10.1016/0922-4106(94)90196-1.

Abstract

The binding characteristics of [3H]mepyramine to histamine H1 receptors in the smooth muscle cell line, DDT1MF-2, have been investigated. Competition binding experiments produced dissociation constants (Ki) for mepyramine, (+)-chlorpheniramine, and promethazine of 3.4 nM, 2.6 nM and 0.66 nM, respectively. Saturation binding using [3H]mepyramine produced a Kd of 2.1 nM and a Bmax of 47 fmol/mg protein. These data suggest that a high-affinity [3H]mepyramine binding site can be detected with the characteristics of the "classical" histamine H1 receptor. The low-affinity [3H]mepyramine binding site reported previously [Mitsuhashi, M. and Payan, D.G. (1988) J. Cell. Physiol. 134, 367-375] is predominantly to a secondary [3H]mepyramine site. The "low affinity" or secondary [3H]mepyramine binding site on DDT1MF-2 cells is insensitive to quinine (10 microM) and is therefore distinct from the [3H]mepyramine binding protein found in rat liver.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites
  • Binding, Competitive
  • Cells, Cultured
  • Cricetinae
  • Male
  • Muscle, Smooth / metabolism*
  • Pyrilamine / metabolism*
  • Quinine / pharmacology
  • Receptors, Histamine H1 / metabolism*
  • Vas Deferens / metabolism

Substances

  • Receptors, Histamine H1
  • Quinine
  • Pyrilamine