Abstract
We investigated the contraction responses of isolated guinea-pig ileum preparations under several conditions of electrical field stimulation. Histamine H3-agonists caused a dose-dependent inhibition of both cholinergic and nonadrenergic noncholinergic (NANC) responses (pD2 of histamine, 7.3; N alpha-methylhistamine, 8.4; (R)-alpha-methylhistamine, 8.3); H3-antagonists blocked this inhibition (pA2 of impromidine, 7.2; thioperamide, 8.5). Our results indicate that H3-receptors are present on both cholinergic and NANC nerves in the myenteric plexus and that the preparation can be used as a rapid and simple test system for histamine H3-receptors.
MeSH terms
-
Animals
-
Atropine / pharmacology
-
Autonomic Nervous System / drug effects
-
Electric Stimulation
-
Guanidines / pharmacology
-
Guinea Pigs
-
Histamine / pharmacology
-
Ileum / drug effects
-
Imidazoles / pharmacology
-
Impromidine
-
In Vitro Techniques
-
Male
-
Methylhistamines / pharmacology
-
Muscle Contraction / drug effects
-
Muscle, Smooth / drug effects*
-
Muscle, Smooth / physiology
-
Myenteric Plexus / drug effects
-
Parasympathetic Nervous System / drug effects
-
Piperidines / pharmacology
-
Receptors, Histamine / physiology*
-
Receptors, Histamine H3
-
Tetrodotoxin / pharmacology
Substances
-
Guanidines
-
Imidazoles
-
Methylhistamines
-
Piperidines
-
Receptors, Histamine
-
Receptors, Histamine H3
-
Tetrodotoxin
-
Atropine
-
Histamine
-
Impromidine
-
thioperamide
-
N-methylhistamine