Volume 115, Issue 3, Pages 672-679 (September 1998) Somatostatin stimulates the brush-tailed possum sphincter of Oddi in vitro and in vivo  Jiaqing Huang, Robert T.A. Padbury, Ann C. Schloithe, Michael R. Cox, Maria E. Simula, John R. Harvey, Robert A. Baker, James Toouli, Gino T.P. Saccone  Gastroenterology  Volume 115, Issue 3, Pages 672-679 (September 1998) DOI: 10.1016/S0016-5085(98)70146-5 Copyright © 1998 American Gastroenterological Association Terms and Conditions

Fig. 1 Distribution of SOM-like immunoreactivity in sections of the sphincter of Oddi. SOM-IR nerve fibers (arrows) in the muscle layer (M) and in a nerve bundle (arrowhead). Red blood cells in the muscle layer and subepithelial plexus (E) are indicated by asterisks (bar = 50 μm). Gastroenterology 1998 115, 672-679DOI: (10.1016/S0016-5085(98)70146-5) Copyright © 1998 American Gastroenterological Association Terms and Conditions

Fig. 2 The effect of SOM 1–14 on sphincter of Oddi muscle strip activity, sphincter of Oddi motility, and transsphincteric flow. (A) SOM 1–14 (10−6 mol/L) increased the frequency and amplitude of contraction by SOC and SOL muscle strips. (B) SOM 1–14 (100 ng/kg) stimulated sphincter of Oddi (SO) contraction frequency and amplitude with a concurrent reduction in transsphincteric flow (lower trace). (C) SOM 1–14 (2000 ng/kg) increased sphincter of Oddi basal pressure, contraction frequency, and amplitude (upper) with abolition of transsphincteric flow (lower). The rapid pen upstrokes in the transsphincteric flow recordings represent rapid additions of 500 μL saline to the inflow reservoir to maintain a constant inflow pressure. The broken line indicates the basal pressure before the addition of SOM 1–14. Gastroenterology 1998 115, 672-679DOI: (10.1016/S0016-5085(98)70146-5) Copyright © 1998 American Gastroenterological Association Terms and Conditions

Fig. 3 Concentration-dependent stimulation of SOC and SOL muscle strip contraction amplitude by SOM 1–14 with and without TTX pretreatment. SOM 1–14 induced a concentration-dependent increase in the amplitude of contractions (●) of (A) SOC and (B) SOL muscle strips. However, pretreatment of muscle strips with 10−6 mol/L TTX (○) only reduced the SOM 1–14–induced SOL contraction amplitude (P < 0.0001, ANOVA). Data are expressed as the means ± SEM (n = 9–11 animals). Gastroenterology 1998 115, 672-679DOI: (10.1016/S0016-5085(98)70146-5) Copyright © 1998 American Gastroenterological Association Terms and Conditions

Fig. 4 Changes in sphincter of Oddi motility and transsphincteric flow induced by graded doses of SOM 1–14. (A) Administration of 50–2000 ng/kg SOM 1–14 did not change sphincter of Oddi (SO) basal pressure in a dose-dependent manner throughout the full dose range; however, significant increases were noted with the three highest doses (500, 1000, and 2000 ng/kg; *P < 0.05, paired t test with Bonferroni correction). SOM 1–14 stimulated sphincter of Oddi contraction (B) amplitude and (C) frequency in a dose-dependent manner (P < 0.001 and P < 0.05, ANOVA, respectively). (D) SOM 1–14 decreased transsphincteric flow (TSF) in a dose-dependent manner (P < 0.0001, ANOVA). Data are expressed as the percent of control and expressed as the means + SEM (n = 7 animals). Gastroenterology 1998 115, 672-679DOI: (10.1016/S0016-5085(98)70146-5) Copyright © 1998 American Gastroenterological Association Terms and Conditions

Fig. 5 Effect of SOM 1–14 on sphincter of Oddi (SO) motility and transsphincteric flow before and after pretreatment with TTX. The action of SOM 1–14 (200, 500, and 2000 ng/kg) on (A) sphincter of Oddi basal pressure, (B) frequency, (C) contraction amplitude, and (D) transsphincteric flow (TSF) was not influenced by pretreatment with 9 μg/kg TTX administered by close intra-arterial injection (Wilcoxon signed-rank test). The data are expressed as the mean percent of control ± SEM. □, No TTX pretreatment; ▩, TTX pretreatment (n = 6 animals). Gastroenterology 1998 115, 672-679DOI: (10.1016/S0016-5085(98)70146-5) Copyright © 1998 American Gastroenterological Association Terms and Conditions