Changes in the molecular composition of circulating hydroxyethyl starch following consecutive daily infusions in man

1 Changes in the circulating molecular composition of hydroxyethyl starch (HES) were determined in four normal men following three consecutive daily 500 ml infusions (total 1,500 ml), by passage of trichloroacetic acid filtrates of plasma through a Sepharose CL4B gel filtration column. 2 The HES recovered from the intravascular space 10 min following the injection on Days 1, 2 and 3, was of a narrower molecular size distribution than the injected material, with a noticeable shift to molecules of a low molecular weight (LMW) size. 3 The HES in the sampled plasma 24 h post-injection on Days 1, 2 and 3 consisted of molecules possessing a LMW distribution, concomitantly with a slight shift to molecules of a larger molecule size. 4 The HES recovered from the bloodstream 480 h after the third and final injection consisted of molecules possessing an intermediate size distribution, between LMW and high molecular weight (HMW) size material. 5 The results indicate that large HES molecules contained in the injected material are eliminated from the bloodstream; the HMW fraction at least partially by a alpha-amylase mediated catabolism, and the resulting LMW fraction by excretion.