Catabolism of low-molecular-weight hydroxyethylated amylopectin in man. I. Changes in the circulating molecular composition.

Intravascular persistence concomitant with changes in the circulating molecular composition were determined in six fasted normal men dosed with 400 ml of 14% LMW-HES (a new plasma expander). The concentration of LMW-HES in serum fell to half its peak value in 3.9 +/- 1.1 (S.D.) hr, whereas serum levels of glucose remained elevated throughout the 12 hr postinjection fasting period. The LMW-HES recovered from the intravascular space was shown by gel filtration on a column of Sepharose CL-4B to be a narrower molecular size distribution (less polydispersion) than the injected material. The ratio of Kav . urine/Kav . injected solution was 1.34. At 30 min after injection, however, the ratio of Kav . urine/Kav . serum was 1.20, and by 24 hr, the value was 1.15. Overall, changes in the molecular distribution in the bloodstream between the end of the infusion period and 24 hr later were small. The results suggest that the intravascular catabolism of LMW-HES may occur in two distinct phases: a rapid initial degradation, followed by a more gradual elimination influenced by the MS of the injected material.