Splanchnic hemodynamics in portal-hypertensive rats: measurement with gamma-labeled microspheres

A method to quantitate hepatic arterial flow (HA), portal venous flow (PBF), and blood flow through portal-systemic shunts (ShBF) in portal-hypertensive rats is described. This method relies on the injection of two differently radiolabeled microspheres (15 micrometers) into the left ventricle and spleen. To evaluate the usefulness of this technique, studies were performed on normal, cirrhotic, and portal vein-ligated rats anesthetized with ketamine. With this method, PBF is calculated indirectly from the sums of the blood flow of the splanchnic organs that drain into the portal vein. In the portal-hypertensive animals with portal-systemic shunting, this technique allows for the determination of PBF perfusing the liver [hepatic fraction of portal flow (HFP)] and PBF escaping through portal-systemic shunts (ShBF). The portal vein-ligated rats have higher HA flow (0.68 +/- 0.08 ml . min-1 . g-1) and lower HFP (0.08 +/- 0.01 ml . min-1 . g-1) than either the cirrhotic (HA: 0.27 +/- 0.03 ml . min-1 . g-1, P less than 0.01; HFP: 1.20 +/- 0.20 ml . min-1 . g-1, P less than 0.01) or the normal rat (HA: 0.29 +/- 0.06 ml . min-1 . g-1, P less than 0.01; HFP: 1.39 +/- 0.16 ml . min-1 . g-1, P less than 0.01). No significant difference was found between the cirrhotic and normal rats. The ShBF was higher in the portal vein-ligated rats (21.4 +/- 2.8 ml/min) than in the cirrhotic (4.6 +/- 2.5 ml/min, P less than 0.001) or normal rats (0.03 +/- 0.005 ml/min, P less than 0.01). The difference between the cirrhotic and normal animals was also significant (P less than 0.05). This is a simple, rapid, and reliable technique that allows for the quantitation of splanchnic hemodynamics in experimental models with portal hypertension.