Differently Labelled Glucosamine‐Precursor Pooles for the Biosynthesis of Hyaluronate and Heparan Sulfate

14C‐labelled hyaluronate and heparan sulfate were isolated from bovine arterial tissue following incubation in vitro in the presence of [U‐14C]glucose and [1‐14C]glucosamine, respectively. The specific radioactivity of hyaluronate was higher than that of heparan sulfate, but the ratio of their specific radioactivities (hyaluronate/heparan sulfate) was 2.5 or 1.2, depending on whether [14C]glucose or [14C]glucosamine was used as the metabolic precursor. In the [14C]glucose experiments the proportion of radioactivity incorporated into the glucosamine and glucuronic acid moiety of hyaluronate was about 1:1, while in the case of heparan sulfate the corresponding ratio was 1:1.7. Values of 3.3 and 1.1 were calculated for the specific radioactivity ratio of the glucosamine moiety of hyaluronate and heparan sulfate (glucosamine‐hyaluronate/glucosamine‐heparan sulfate) following labelling with [14C]glucose and [14C]glucosamine, respectively. The results are consistent with the assumption that two topographically different pools of immediate metabolic precursors exist in bovine arterial cells, one being for the biosynthesis of hyaluronate and the other for heparan sulfate.