Effect of moderate haemodilution with Fluosol-DA or normal saline on indocyanine green and (+)-propranolol kinetics

Indocyanine green (ICG) and (+)-propranolol kinetics were determined in the rat following moderate (50%) blood exchange with either Fluosol-DA or 0.9% NaCl (saline). Rats received an intravenous ICG dose (5 mg kg-1) before an intravenous dose of (+)-propranolol (2.5 mg kg-1) 0.5, 24, 48 or 72 h after haemodilution and were compared with non-exchanged controls. Haemodilution with Fluosol-DA reduced the ICG elimination rate constant during the first 24 h while a significant reduction was seen 48 h after normal saline exchange. ICG clearances tended to be less than the control value, and were significantly reduced only at 24 h after Fluosol-DA exchange due to a reduced Varea. (+)-Propranolol half-life was significantly increased 48 and 72 h after saline exchange; (+)-propranolol clearance was also significantly reduced 72 h after Fluosol-DA exchange. ICG clearance may be reflecting a hypovolaemic change which occurs after haemodilution, which would reduce the hepatic blood flow. However, (+)-propranolol clearance was not altered, suggesting that the hepatic blood flow is not changed. It is possible that ICG clearance is changed due to alterations in its extraction ratio instead of hepatic blood flow changes.