From the Department of Pharmacology, Medical Faculty, Kragujevac, Serbia, FR Yugoslavia
Abstract: (4078 Views)
Up to date, there are four pharmacologically characterized subtypes of
muscarinic receptors (M1, M2, M3 and M4). In our study we have investigated
muscarinic receptor subtypes in smooth muscle layers of human stomach. Isolated
preparations of longitudinal and circular muscle layers from human stomach were
used. Acetylcholine, bethanechol, carbachol, pilocarpine and AHR -602 produced
concentration-dependent tonic contractions of isolated preparations of both
longitudinal and circular muscle layers. Only pilocarpine increased the amplitude
of spontaneous contractions of circular muscle preparations.
Atropine, trihexyphenidyl, pirenzepine, telenzepine, hexocyclium, gallamine
and scopolamine butylbromide concentration-dependently blocked tonic
contractions of isolated preparations of both circular and longitudinal muscle
layers caused by acetylcholine. Pancuronium did not block tonic contractions
caused by acetylcholine, while para-fluoro-hexahydro-sila-difenidol (pFHHSiD)
produced weak concentration-dependent blockade of tonic contractions caused by
acetylcholine in circular muscle preparations only. The most potent antagonists
were M1 selective antagonists: trihexyphenidyl, telenzepine and hexocyclium.
These results suggested a predominance of the M1 muscarinic receptor subtype in
smooth muscle of the human stomach.