Apparatus used in the ex vivo studies in intestine: (a) disposable syringe for collection of serosal fluid, (b) hypodermic needle, (c) rubber stopper, (d) conical flask, (e) polyethylene centrifuge tube, (e) water bath (37°C), (g) tape used to fasten intestine to tube, (h) intestine, (i) mixture of gas inlet (O₂ 95% and CO₂ 5%), and (j) disposable plastic syringe used to collect mucosal fluid.