Page 49 - Human Bile Acid Metabolism: a Postprandial Perspective

and the anaesthesia continued with isoflurane (2%). In total, we implanted 7 intravascular catheters (Fig. 1) as well as a feeding tube inserted percutaneously into the stomach.
In order to measure organ fluxes, we placed two catheters upstream of the organs
for para-aminohippuric acid (PAH) infusion. For muscle flux measurements, we
implanted the PAH infusion catheter into the abdominal aorta with its tip 5 cm 3 above the bifurcation and the other PAH infusion catheter into the splenic vein. We
inserted sampling catheters into the abdominal aorta above the right renal artery (A)
for pre-organ compartment arterial plasma concentrations; into the inferior caval
vein (iliac circumflex profunda vein) (V) with its tip 5 cm above the bifurcation
for muscle flux measurements and venous concentrations; into the left renal vein
(R) for kidney flux measurements; into the portal vein with its tip in the liver hilus
(P), and into the hepatic vein (H) by direct puncture of the liver for the splanchnic measurements. To reassure that the catheter H was correctly placed in the hepatic
vein, we punctured the external side of the liver and pushed in the catheter for 20
cm, then we retracted it to 5 cm to ensure we were not in the inferior caval vein. We
secured all catheters in place and tunnelled them through the left abdominal wall.
After abdominal closure the pigs were dressed with a canvas harness to protect the
catheters. To keep the catheters patent they were filled with 0.5 mL of gentamycine
(20 mg/mL) and a-chymotrypsin solution (225 U/mL).
After surgery we checked the animals twice daily for four days on body temperature, catheter patency and overall behaviour. Also, animals received i.v. injections with antibiotics (6.25 mg/kg lincomycin and 12.5 mg/kg spectinomycin) and analgetics (2 mg/kg flunixin meglumine) and the animals were allowed to recover for 7-10 days. During this period they were also habituated to the experimental cage (0.9 × 0.5 × 0.3 m on wheels).
Experimental procedure
The animals were conscious during the whole experimental procedure. We removed all food at 16:00 h the day before the experiment. On the day of the experiment all animals were first weighed and at 08:00 h (t = - 60 min), an hour before the meal, we started the continuous infusion of 25 mM PAH at 60 mL/h and reached steady state before the sampling started. At t = -10,- 5 and 0 min, we took three baseline blood samples from all catheters. Samples were always taken
Transhepatic bile acid kinetics
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