Metabolism of the human serum beta-hexosaminidase isoenzymes in the rat: an in vivo and in vitro study.

Plasma clearance of purified human serum beta-hexosaminidase isoenzymes was studied in the rat. The serum beta-hexosaminidase isoenzymes (A, B and P) showed a slow clearance from circulation compared to their tissue counterparts. After desialylation, the clearance rate of all serum isoenzymes was markedly enhanced. The uptake of native as well as desialylated serum beta-hexosaminidase isoenzymes was studied in rat liver nonparenchymal cells and hepatocytes. No detectable uptake of any native serum isoenzyme was noticed in either cell type. However, when these isoenzymes were desialylated by neuraminidase treatment, isoenzymes A and B were taken up by the nonparenchymal cells. No uptake was observed for the P form. None of the desialylated serum forms was taken up by hepatocytes.