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Substance P stimulates sphincter of Oddi motility and inhibits trans‐sphincteric flow in the Australian brush‐tailed possum
Author(s) -
Cox M. R.,
Padbury R. T. A.,
Harvey J. R.,
Baker R. A.,
Toouli J.,
Saccone G. T. P.
Publication year - 1998
Publication title -
neurogastroenterology and motility
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.489
H-Index - 105
eISSN - 1365-2982
pISSN - 1350-1925
DOI - 10.1046/j.1365-2982.1998.00090.x
Subject(s) - substance p , sphincter of oddi , motility , medicine , endocrinology , tetrodotoxin , in vivo , chemistry , contraction (grammar) , anatomy , biology , neuropeptide , receptor , microbiology and biotechnology , genetics
Substance P containing nerves are widely distributed throughout the gastrointestinal tract. The aims of this study were to determine the distribution of substance P containing nerves in the extrahepatic biliary tree of the Australian brush‐tailed possum and to characterize the effect of exogenous substance P on the sphincter of Oddi (SO) motility and trans‐sphincteric flow in vivo. Immunohistochemical staining of fixed specimens (n = 8) found moderate numbers of substance P containing nerve cell bodies and fibres throughout the neural plexuses of the SO, in particular in the serosal and intraluminal nerve trunks of the SO and gallbladder. Synthetic porcine substance P (1–2000 ng kg −1 ), administered by close intra‐arterial injection (i.a. n = 7), produced a dose‐dependent elevation in basal pressure [P < 0.01] and an associated dose‐dependent reduction in trans‐sphincteric flow [P < 0.0001]. Substance P had no significant dose‐dependent effect on SO phasic contraction amplitude or frequency. Tetrodotoxin (9 μg kg −1 , i.a.) did not inhibit the effect of substance P on SO motility and trans‐sphincteric flow (n = 5). In conclusion, substance P containing nerves are found throughout the possum extrahepatic biliary tree. Exogenous substance P stimulates SO motility and reduces trans‐sphincteric flow in vivo by acting directly on the sphincter smooth muscle.