title: Radiation-induced changes in the cell membrane of cultured human endothelial cells.
abstract: We investigated the effect of irradiation on the kinetic characteristics of amino acid and glucose transport, and the effect on the activity of the cell membrane-bound enzyme 5'-nucleotidase and on the receptor-mediated stimulation of cyclic adenosine monophosphate synthesis by prostaglandin E1. Irradiation inhibited the sodium-dependent amino acid transport by a reduced binding of the amino acid to the transport unit. The transport of glucose, which appeared to be a sodium-independent process, was temporarily stimulated by increased maximal velocity of the transport. No effect was found on the binding to the transport unit. Irradiation increased the 5'-nucleotidase activity and decreased the prostaglandin E1-stimulated cyclic adenosine monophosphate synthesis 48 h after exposure to 20 Gy. It is concluded that irradiation decreases sodium-dependent transport by impairment of the transport unit, does not impair a sodium-independent process, and has opposite effects on membrane-bound enzyme activity and a receptor-mediated process.
mesh_terms: D015720:5'-Nucleotidase; D000527:Alprostadil / Q000494:pharmacology; D000596:Amino Acids / Q000378:metabolism; D001692:Biological Transport / Q000528:radiation effects; D002462:Cell Membrane / Q000378:metabolism / Q000528:radiation effects*; D000242:Cyclic AMP / Q000096:biosynthesis; D005947:Glucose / Q000378:metabolism; D006801:Humans; D009708:Nucleotidases / Q000378:metabolism; D014471:Umbilical Veins / Q000166:cytology
chemical_list: D000596:Amino Acids; D000242:Cyclic AMP; D009708:Nucleotidases; D015720:5'-Nucleotidase; D000527:Alprostadil; D005947:Glucose