Sobrevia, L. and Jarvis, S.M. and Yudilevich, D.L. (1994) Adenosine Transport in Cultured Human Umbilical Vein Endothelia-Cells is Reduced in Diabetes. American Journal of Physiology, 267 (1). C39-C47. ISSN 0002-9513.
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Adenosine transport in cultured human umbilical vein endothelial cells (HUVEC) was characterized and shown to be mediated by a single facilitated diffusion mechanism. Initial rates of adenosine influx at 22 degrees C were saturable [apparent Michaelis constant, 69 +/- 10 mu M; maximum velocity (V-max), 600 +/- 70 pmol.10(6) cells(-1).s(-1)] and inhibited by nitrobenzylthioinosine (NBMPR). Formycin B had an unusually high affinity [inhibitory constant K-i), 18 +/- 4.3 mu M], whereas inosine had a low affinity (K-i, 440 +/- 68 mu M) and nucleobases were without effect on adenosine influx. The number of transporters (1.2 x 10(6) sites/cell) was estimated by NBMPR equilibrium binding (apparent dissociation constant, 0.11 +/- 0.01 nM; maximum binding, 2.0 +/- 0.15 pmol/10(6) cells). In addition, we compared these endothelial cells with those obtained from cords from pregnancies complicated by diabetes (HUVEC-D), since embriopathy may occur in these conditions. HUVEC-D exhibited a 2.3-fold reduction in both the V-max for adenosine influx and the maximum number of NBMPR binding sites (260 +/- 40 pmol.10(6) cells(-1).s(-1) and 0.86 +/- 0.08 pmol/10(6) cells, respectively). However, the turnover number for each nucleoside transporter in normal and diabetic HUVEC was similar (approximate to 300 adenosine molecules/s). Adenosine metabolism at 10 mu M in HUVEC-D was modified compared with normal cells. Intracellular phosphorylation (> 90%) was the predominant pathway in normal HUVEC, whereas in HUVEC-D, substantial levels of adenine and adenosine were detected. The present results demonstrate therefore the downregulation of the NBMPR-sensitive nucleoside transporter and changes in adenosine metabolism in HUVEC from diabetic pregnancies.
|Uncontrolled keywords:||NUCLEOSIDE TRANSPORTER; NITROBENZYLTHIOINOSINE; DIABETIC PREGNANCY|
|Subjects:||B Philosophy. Psychology. Religion > B Philosophy (General)|
|Divisions:||Faculties > Social Sciences > School of Psychology|
|Depositing User:||P. Ogbuji|
|Date Deposited:||18 Jun 2009 11:28|
|Last Modified:||17 Jul 2012 11:01|
|Resource URI:||http://kar.kent.ac.uk/id/eprint/20052 (The current URI for this page, for reference purposes)|
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