Muscarinic receptor subtypes of guinea-pig common bile duct.
The antagonism of carbachol-induced contractions of guinea-pig common bile duct smooth muscle strips by various antagonists has been investigated in order to find out the muscarinic receptor subtype(s) of common bile duct smooth muscle. Atropine, pirenzepine, 4-DAMP and AF-DX 116 were used as nonselective, M1-selective, M1- and M3-selective and M2-selective muscarinic antagonists, respectively. All muscarinic antagonists examined displaced the concentration-response curves to the right, parallelly and in a concentration-dependent manner, without affecting maximum response. Schild analysis of data was consistent with competitive antagonism. pA2 values of the antagonists were as follows: atropine, 9.59; pirenzepine, 7.32; 4-DAMP, 8.99; AF-DX 116, 6.85. When these pA2 values are compared with those obtained in the ileum, it may be concluded that the muscarinic receptors of the guinea-pig common bile duct mediating cholinomimetic-induced contractions, are of the M3 subtype, but not of the M1 and M2 subtypes.
Karahan
F
F
Department of Pharmacology, Marmara University School of Medicine, Turkey.
Alican
I
I
Ozkutlu
U
U
Onat
F
F
Yegen
B C
BC
Ulusoy
N B
NB
Oktay
S
S
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D003135:Common Bile Duct / Q000294:innervation*; D005260:Female; D006168:Guinea Pigs; D008297:Male; D018727:Muscarinic Antagonists; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000294:innervation* / Q000502:physiology; D010276:Parasympatholytics / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology; D010890:Pirenzepine / Q000031:analogs & derivatives / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000378:metabolism*
D018727:Muscarinic Antagonists; D010276:Parasympatholytics; D010880:Piperidines; D011976:Receptors, Muscarinic; D010890:Pirenzepine; D001285:Atropine; C042375:4-diphenylacetoxy-1,1-dimethylpiperidinium; D002217:Carbachol; C048593:otenzepad