EFFECTS OF INTRAVENOUS PENTAFRACTION ON LUNG AND SOFT-TISSUE LIQUID EXCHANGE IN HYPOPROTEINEMIC SHEEP

Effects of infusing pentafraction (Pen), a synthetic hydroxyethyl star ch plasma volume expander, on lung and soft tissue lymph flux were com pared in nonanesthetized sheep that were protein depleted by batch pla smapheresis. Pen (5%) was infused to raise pulmonary arterial wedge pr essure by 5 mmHg for 2 h (1.8 +/- 0.3 1). Pen raised plasma osmotic pr essure from plasmapheresis baseline (10.7 +/- 2.2 mmHg; preplasmaphere sis baseline, 19.6 +/- 0.6 mmHg) to 16.6 +/- 2.4 mmHg. After Pen, lung lymph flows peaked at 3.9 +/- 2.0 times a preplasmapheresis baseline value of 1.0 (plasmapheresis baseline, 2.7 +/- 0.7), but soft tissue l ymph flows rose insignificantly. Plasma Pen concentrations were 2.3 +/ - 1.0% postinfusion and 1.6 +/- 0.3% at 12 h. Pen mean molecular masse s at these times, measured by high-performance liquid chromatography, were 160 +/- 44 and 129 +/- 23 kDa, respectively. In lung lymph, Pen c oncentrations were 0.8 +/- 0.6% postinfusion and 0.7 +/- 0.2% at 12 h, with mean molecular masses of 125 +/- 44 and 112 +/- 18 kDa, respecti vely. In soft tissue lymph Pen was nearly undetectable postinfusion, b ut at 12 h concentrations averaged 0.3 +/- 0.2% with a mean molecular mass of 80 +/- 10 kDa. The osmotic effectiveness of Pen may be related to its molecular mass, which was large enough to restrict filtration so that the plasma-to-lung lymph osmotic pressure gradient widened. Pe n remained effective in the circulation for at least 24 h.