An experimental method for study of liver blood flow and metabolism in intact animals

Abstract

A method for studying liver circulation and liver metabolism in awake animals is described. Total liver blood flow was measured by xenon clearance and portal flow measured shortly thereafter by the same technique during brief occlusion of hepatic artery. When xenon clearance flow values were compared with electromagnetic flowmeter measurements made at the time of surgery, there was an excellent correlation among 21 measurements in 11 pigs ( r=0.94). Using a special technique, placement of a chronic inlying hepatic vein catheter was achieved. Together with inlying arterial and portal catheters, this made it possible to study liver metabolism at 2 to 3 days and at 7 days postoperatively. Although portal flow was the same early and late postoperatively, hepatic artery flow was twice as high in the earlier group of animals. Two to three days postoperatively there was a net hepatic uptake of total amino acids amounting to 5.6 ± 2.1 μmole/min × kg body wt −1. One week after surgery a net release of 3.2 ± 1.9 μmole/min × kg −1 ( P < 0.01) was observed. This useful experimental preparation demonstrates both changes of liver blood flow and in hepatic uptake and utilization of amino acids released at a high rate by peripheral tissues after trauma. It also seems to demonstrate that pigs fed a normal diet have recovered from trauma of surgery after one week. The method offers means to study liver circulation and metabolism in a wide variety of experiments.