Nucleoside uptake by red blood cells from a primitive vertebrate, the Pacific hagfish (Eptatretus stouti), is mediated by a nitrobenzylthioinosine-insensitive transport system.
Red blood cells from the Pacific hagfish (Eptatretus stouti) were found to possess a facilitated diffusion nucleoside transport system insensitive to inhibition by the nucleoside transport inhibitor nitrobenzylthioinosine (NBMPR). Uridine uptake by this route was saturable (apparent Km 0.14 mM; Vmax 2 mmol/l cells per h at 10 degrees C), inhibited by inosine and adenosine, and blocked both by the vasodilator dipyridamole and by the thiol-reactive agent p-chloromercuriphenylsulphonate. The properties of this carrier resemble closely those of NBMPR-insensitive nucleoside transport systems in some mammalian neoplastic cell lines and in rat red cells. The presence of this type of carrier in a primitive vertebrate suggests that such transporters have a broad biological distribution and that they pre-date or arose at an early stage of vertebrate evolution.
Department of Physiology, University of Alberta, Edmonton, Canada.
D A
DA
Fincham
M W
MW
Wolowyk
J D
JD
Young
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D006196:Hagfishes; D009705:Nucleosides / Q000097:blood*; D013868:Thioinosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology*
D009705:Nucleosides; D013873:Thionucleotides; D013868:Thioinosine; C028318:nitrobenzylthioinosine 5'-monophosphate