A study of the histamine H2-receptor mediating relaxation of the parenchymal lung strip preparation of the guinea-pig

Br J Pharmacol. 1985 Oct;86(2):465-73. doi: 10.1111/j.1476-5381.1985.tb08916.x.


The relaxation produced by several H2-receptor agonists and forskolin was investigated on strips of guinea-pig lung parenchyma. Dimparit, 1 microM to 10 mM, 4-methyl histamine, 0.5 microM to 100 microM and impromidine, 10 nM to 1 microM, had no effect on the tone of the unstimulated strips of lung parenchyma but caused a dose-dependent relaxation of strips that were contracted by 2-pyridylethylamine (2-PEA), 15 microM. Forskolin, 10 nM to 4 microM, produced a dose-dependent relaxation of both the stimulated and unstimulated lung strips. The muscarinic antagonist atropine, 1 microM, and the beta 2-adrenoceptor antagonist propranolol, 10 microM, had no effect on the dose-response curve for dimaprit-induced relaxation of the lung strip. The dose-response curve for dimaprit was shifted to the right in a dose-dependent manner by increasing concentrations of a variety of H2-antagonists. Schild plots produced a straight line for all the H2-antagonists with slopes not significantly different from unity. The equilibrium dissociation constants for the H2-antagonists on the lung strip preparation were similar to those previously reported for inhibition of the chronotropic activity of histamine on guinea-pig right atria and inhibition of [3H]-tiotidine binding to homogenates of guinea-pig lung parenchyma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Atropine / pharmacology
  • Colforsin / pharmacology
  • Dimaprit
  • Female
  • Guinea Pigs
  • In Vitro Techniques
  • Lung / drug effects
  • Male
  • Muscle Relaxation / drug effects
  • Muscle, Smooth / drug effects*
  • Propranolol / pharmacology
  • Pyridines / pharmacology
  • Receptors, Histamine / physiology*
  • Receptors, Histamine H2 / physiology*
  • Thiourea / pharmacology


  • Pyridines
  • Receptors, Histamine
  • Receptors, Histamine H2
  • Colforsin
  • Atropine
  • Propranolol
  • 2-(2-aminoethyl)pyridine
  • Thiourea
  • Dimaprit