Endogenous Nucleosides in the Guinea-pig Eye: Analysis of Transport and Metabolites
This study investigates the transport of endogenous nucleosides and deoxynucleosides from the capillaries of the eye into the aqueous humour and the lens using thein situvascular eye perfusion technique in the guinea-pig. The transport of [3H] adenosine and [3H] thymidine across the blood-aqueous ba...
Saved in:
| Published in: | Experimental eye research Vol. 66; no. 3; pp. 315 - 325 |
|---|---|
| Main Authors: | , , , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
London
Elsevier Ltd
01-03-1998
Elsevier |
| Subjects: | |
| Online Access: | Get full text |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | This study investigates the transport of endogenous nucleosides and deoxynucleosides from the capillaries of the eye into the aqueous humour and the lens using thein situvascular eye perfusion technique in the guinea-pig. The transport of [3H] adenosine and [3H] thymidine across the blood-aqueous barrier proved to be very rapid with a volume of distribution after 4 minutes perfusion reaching 11.9±3.0% and 9.93±1.1%, respectively. However, the transport of [3H] guanosine and [3H] cytidine was slower, with volumes of distribution reaching only 3.38±0.58% and 4.8±1.41%. The values for the entry of deoxyadenosine and deoxyguanosine were not significantly different from the values obtained for corresponding ribonucleosides (adenosine and guanosine) so that a change in the pentose sugar does not change the affinity of the nucleoside for the transport protein. Perfusion with a low sodium medium inhibited the transport of [3H] adenosine and [3H] thymidine into the aqueous humour. The presence of 800 nMNBTI also caused a decrease in adenosine transport into the aqueous humour, so that the volume of distribution after 2 minutes reached only 3.78±1.87%. These findings suggest that the transfer of adenosine across the blood-aqueous barrier has both concentrative and equilibrative components. The presence of 0.1 mMthymidine had no effect on the [3H] adenosine transport, whereas 0.1 mMof adenosine resulted in a marked decrease on the [3H] thymidine transport which suggests that the concentrative nucleotide transport is probably mediated by bothcifandcittransport systems. The cellular uptake of nucleosides into the lens was very rapid and the volume of distribution of purine nucleosides was within the range of 30–50% whereas that for thymidine uptake was somewhat lower, reaching 20–30%. HPLC analysis of the eye structures in the guinea-pig showed that lens, vitreous body and the rest of the eye do not contain either free nucleosides or purine bases in detectable quantities, except for xanthine which was detected in aqueous humour at a concentration of 2.51±0.51 mM.However, serum of the anaesthetised guinea-pig did not contain xanthine in detectable amount so it seems that the metabolic degradation of the nucleosides in the guinea-pig eye progresses as far as xanthine, which is then accumulated in the aqueous humour. |
|---|---|
| Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 0014-4835 1096-0007 |
| DOI: | 10.1006/exer.1997.0424 |