A MODEL FOR THE EXTENDED STUDIES OF HEPATIC HEMODYNAMICS AND METABOLISM IN SWINE

To our knowledge postoperative hepatic hemodynamics and hepatic metabo lism have not been fully studied on a long-term basis. Our goal was to develop a large animal model that would permit the measurement of hep atic blood flow (BF), perihepatic pressures (P), and hepatic metabolis m in a long-term setting. Catheters were inserted into the jugular vei n, carotid artery, pulmonary artery, hepatic vein, and portal vein (PV ) of 27 commercially bred pigs; ultrasonic transit time flowmeter prob es were placed around the hepatic artery and PV. Daily postoperative m easurements of jugular vein P, carotid artery P, pulmonary artery P, h epatic vein P, and PVP, as well as hepatic artery BF and PVBF, were re corded for 20 days. Hepatic carbohydrate metabolism was assessed by ar teriovenous difference techniques. Jugular vein P, pulmonary artery P, hepatic vein P, PVP, and heart rate reached steady-state values durin g the first week, with a mean +/- SEM of 1.0 +/- 0.3 mm Hg for jugular vein P, 21.4 +/- 2.1 mm Hg for pulmonary artery P, 4.3 +/- 0.4 mm Hg for HVP, 7.8 +/- 0.5 mm Hg for PVP, and 116 +/- 4 beats per minute for heart rate. Mean carotid artery P increased from 65 +/- 3 mm Hg durin g surgery to 94 +/- 2 mm Hg on postoperative day 1 (P < 0.001) and to a mean 101 +/- 2 mm Hg thereafter. Total hepatic BF reached a steady-s tate value of 1,132 +/- 187 ml/min by postoperative day 7 (P = 0.19). Over week 1 hepatic artery BF measured as a percentage of total hepati c BF decreased from 35.0 +/- 3.0% to 15.5 +/- 2.7%, and PVBF increased from 65.0 +/- 3.0% to 84.5 +/- 2.7% (P < 0.005); both variables were steady thereafter. In the hemodynamic steady state the net hepatic bal ances of glucose, lactate, glycerol, and alanine in 5 pigs were 9.9 +/ - 4.0, -4.2 +/- 0.4, -2.3 +/- 1.1, and -0.68 +/- 0.22 mu mol/kg per mi n respectively. The net gut (portal-drained visceral balances of gluco se, lactate, alanine, and glycerol were -2.0 +/- 2.5, 1.1 +/- 0.5, 0.7 3 +/- 0.18, and -0.69 +/- 0.19 mu mol/kg per min respectively. Thus, a reliable large animal model was developed to study acute and chronic hepatic hemodynamics and metabolism.