Hemodynamic changes after hepatectomy in rats studied with radioactive microspheres.

It has been difficult to measure hepatic arterial blood flow and portal venous flow simultaneously, especially in small animals. Radioactive microspheres were used in this experiment to quantitate splanchnic hemodynamics after hepatectomy in rats. With a reference sample technique, a certain amount of radioactive microspheres was injected into the left ventricle. The reference sample was withdrawn from the femoral artery at a constant rate. The animal was killed with a bolus of saturated KCl. The kidneys and splanchnic organs were removed and weighed. The radioactivity of each organ was determined using a gamma scintillation counter. Organ blood flow was calculated by the following formula: [formula: see text] Immediately after partial hepatectomy, a decreased cardiac index from 32.31 +/- 10.12 to 23.44 +/- 3.21 ml/(min x 100g body weight) (p less than 0.05), decreased hepatic arterial blood flow from 0.40 +/- 0.12 to 0.33 +/- 0.03 ml/(min x g liver) (p less than 0.05), increased portal venous inflow from 0.90 +/- 0.30 to 2.20 +/- 0.26 ml/(min x g liver) (p less than 0.05) and increased total hepatic blood flow from 1.30 +/- 0.39 to 2.53 +/- 0.26 ml/(min x g liver) (p less than 0.005) were observed. With an intrasplenic injection of an additional amount of radioactive microspheres, the ratio of lung/(lung + liver) radioactivities indicated the degree of portal systemic shunt (PSS). Though the portal pressure was elevated after hepatectomy (8.80 +/- 0.7 vs 11.9 +/- 1.7 cm H2O, p greater than 0.05), the extent of PSS was negligible (0.02 +/- 0.01% vs 0.03 +/- 0.01%, p greater than 0.05). The radioactive microspheres with the reference sample technique is a simple, rapid, reliable and reproducible method for investigating the hemodynamic changes following partial hepatectomy.