Influence of a parenteral fish-oil preparation (Omegaven) on erythrocyte morphology and blood viscosity in vitro.

In most studies fish-oil had been administered by enteral route. Recently an parenteral marine fish-oil emulsion has been developed. With an intravenous infusion an immediate effect on the membrane lipid composition of circulating blood cells and endothelial cells may be expected. In this study we assessed the acute effects of a parenteral fish-oil emulsion on blood rheology and erythrocyte morphology in vitro. Blood from 15 healthy young volunteers was incubated in vitro with increasing concentrations of a parenteral fish-oil emulsion (Omegaven) at 37 degrees C for different time periods (2, 20, and 60 min). Plasma and whole blood viscosity were measured using a Couette viscometer. Red blood cell morphology was examined by light and scanning electron microscopy. High plasma concentrations of Omegaven increased whole blood viscosity at high and low shear rate (p<0.01 above 20%vol) and plasma viscosity to a lower extent (p<0.05 at 40%vol). Erythrocytes underwent cell swelling (increase of centrifuged hematocrit) and a dose-dependent echinocytic shape transformation, which indicates an intercalation of the compound in the outer hemileaflet of the cell membrane. These effects were already apparent after 2 min of incubation and were fully reversible upon wash-out of Omegaven. We conclude that the intravenous fish-oil preparation Omegaven interacts with the outer hemileaflet of the erythrocyte membrane and may affect membrane functions. At pharmacological concentrations these effects seem to be negligeable.