ARE M-CHOLINOCEPTORS OF GUINEA-PIG GALLBLADDER SMOOTH-MUSCLE OF M4 SUBTYPE


OZKUTLU U., ALICAN I., KARAHAN F., ONAT F. , YEGEN B., ULUSOY N., ...More

PHARMACOLOGY, vol.46, no.6, pp.308-314, 1993 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 46 Issue: 6
  • Publication Date: 1993
  • Doi Number: 10.1159/000139061
  • Title of Journal : PHARMACOLOGY
  • Page Numbers: pp.308-314

Abstract

The antagonism of carbachol-induced contractions of guinea pig gallbladder smooth muscle strips via selective antagonists, methoctramine, HHSiD, pf-HHSiD and DABDMA has been investigated in order to find out the m-cholinoceptor subtype(s) of gallbladder smooth muscle. All m-cholinoceptor antagonists examined, displaced the concentration-response curves to the right parallel in a concentration-dependent manner without affecting the maximum response. Schild analysis of data was consistent with competitive antagonism. -log K(B) values of the antagonists were 7.37 for HHSiD, 7.53 for pf-HHSiD, 6.58 for DABDMA and 7.60 for methoctramine. These results, together with the high affinity of pirenzepine and low affinities of 4-DAMP and AF-DX 116, indicate that the m-cholinoceptors of the guinea pig gallbladder which mediate cholinergic contractions are not of m1-, m2- and m3-subtypes but seem likely to be of m4-subtype.