1. Volume 134, Issue 4, Pages 1116-1126 (April 2008)
Cyclic AMP in Rat Ileum: Evidence for the Presence of an Extracellular Cyclic AMP- Adenosine Pathway 
Maria Cecilia Giron, Anna Bin, Paola Brun, Sabrina Etteri, Chiara Bolego, Chiara Florio, Rosa Maria Gaion 
Gastroenterology 
Volume 134, Issue 4, Pages (April 2008)
DOI: /j.gastro
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2. Figure 1
(A) Residual concentration of cAMP and time-dependent conversion of cAMP to (B) AMP, (C) inosine, and (D) adenosine, and (E) total metabolites (AMP + adenosine + inosine) in the medium of freshly isolated ileum strips. Ileum strips were incubated for the indicated times with exogenous cAMP (50 μmol/L; n = 12). #P < .05 versus zero time; *P < .05 versus basal.
Gastroenterology  , DOI: ( /j.gastro )
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3. Figure 2
Linear regression and correlation between tissue protein and (A) cAMP residual concentration or (B) AMP levels in ileum strip medium after 60-minute incubation with cAMP (50 μmol/L; n = 12). (C) Concentration-dependent metabolism of cAMP to AMP and adenosine plus inosine (Ado + Ino) in ileum strip medium after 60-minute incubation with cAMP (50 μmol/L; n = 12). (D) Linear regression and correlation between AMP and Ado + Ino levels (n = 12). *P < .05 versus samples not treated with cAMP.
Gastroenterology  , DOI: ( /j.gastro )
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4. Figure 3
Influence of enzyme inhibitors on cAMP levels and on the accumulation of its metabolites in ileum strip incubation medium. Freshly isolated ileum strips were incubated with cAMP (50 μmol/L) for 60 minutes with or without (A and B) IBMX (1 mmol/L; n = 10), (A and C) DPSPX (1 mmol/L; n = 10), and (A and D) AOPCP (0.2 mmol/L; n = 10). Percent changes in (A) cAMP levels and (B–D) AMP and adenosine + inosine (Ado+Ino; B–D) levels were determined. Influence of an adenosine deaminase inhibitor (1 μmol/L EHNA; n = 6) on (E) cAMP levels and on the accumulation of (F) adenosine (Ado) and inosine (Ino) in the medium of ileum strips incubated with cAMP (50 μmol/L) for 60 minutes. *P < .05 versus basal; #P < .05 and ##P < .01 versus cAMP.
Gastroenterology  , DOI: ( /j.gastro )
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5. Figure 4
Expression of CD73 in rat ileum smooth muscle and ISMCs. (A) CD73 is detected on muscularis externa with higher expression in myenteric plexus (mp) and around cellular membranes of longitudinal muscle (lm) compared with circular muscle (cm). (B) Detailed surface expression pattern of CD73 (green) in subconfluent rat ISMCs. Nuclei were stained with propidium iodide (red). (C) CD73 immunodetection. Lysates of ISMCs, enterocytes, and ileum longitudinal muscle, and nonimmune mouse immunoglobulin G as negative control, were immunoprecipitated with anti-CD73. The specificity of anti-CD73 was shown by a single 70-kilodalton band in the immunoblot (arrow).
Gastroenterology  , DOI: ( /j.gastro )
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6. Figure 5
(A) Concentration-response curve to cAMP in ileum segments. Data are expressed as percent of the maximal contractile response elicited by carbachol (1 μmol/L; n = 12). (B) Influence of adenosine receptor blockade with 8-PT (10 μmol/L; n = 12) or adenosine inhibition with ADA (0.5 U/mL; n = 12) on cAMP-evoked contraction in rat ileum. Data are expressed as percent of the maximal contractile response elicited by cAMP. *P < .01 and **P < .001 versus cAMP. (C) Noncumulative concentration-response curve to forskolin (1–25 μmol/L; n = 6) in ileum segments. Data are expressed as gram tension. #P < .05 versus 1 μmol/L forskolin.
Gastroenterology  , DOI: ( /j.gastro )
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7. Figure 6
[3H]cAMP metabolism and [3H] metabolite accumulation in ileum strip medium during 60-minute incubation (A and B). Ileum strips were incubated with [2,8-3H]cAMP (50 nmol/L; n = 4). (A) Residual [3H]cAMP concentration and formation of its [3H] metabolites ([3H]AMP + [3H]adenosine + [3H]inosine) and [3H]end products ([3H]hypoxanthine + [3H]xanthine + [3H]2O) over time in the incubation medium of freshly isolated ileum strips. (B) Accumulation of [3H]AMP, [3H]adenosine, and [3H]inosine during [3H]cAMP metabolism.
Gastroenterology  , DOI: ( /j.gastro )
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8. Figure 7
Schematic representation of the intestinal cAMP-adenosine pathway. ATP, adenosine triphosphate; ADP, adenosine diphosphate; hormone, adenylyl cyclase–stimulating hormone; R, receptor coupled to adenylyl cyclase (AC); Gs, stimulatory G protein; P1, adenosine receptors; PDE, intracellular phosphodiesterase; 5′-NT, intracellular 5′-nucleotidase; PNP, purine nucleoside phosphorylase; XDH, xanthine dehydrogenase.
Gastroenterology  , DOI: ( /j.gastro )
Copyright © 2008 AGA Institute Terms and Conditions