Please use this identifier to cite or link to this item:
|Title:||Concentrative transport of adenosine in murine splenocytes: Limitation by an ecto-adenosine deaminase||Authors:||Lee, C.-W.
|Issue Date:||1995||Citation:||Lee, C.-W.,Handschumacher, R.E. (1995). Concentrative transport of adenosine in murine splenocytes: Limitation by an ecto-adenosine deaminase. In Vivo 9 (1) : 1-6. ScholarBank@NUS Repository.||Abstract:||Coincident with studies of the transport of (3H]adenosine in murine splenocytes, we have evidence for the extracellular degradation of adenosine. A Na+-dependent active transport system for nucleosides exists in splenocytes, but no intracellular concentration gradient of adenosine was observed. Inhibition of adenosine transport across the plasma membrane by dipyridamole and a Na+-free medium did not prevent the deamination of extracellular adenosine by what has been generally considered to be a cytosolic enzyme. This failure to achieve an Adenosine concentration gradient appears to be consequent to the action of a very active ecto-adenosine deaminase. Inhibition of the adenosine deaminase by deoxycoformycin permits a 6-fold increase in intracellular adenosine concentration relative to the medium by the Na+-dependent process. Rapid inhibition if adenosine deaminase by deoxycoformation occurs even in the presence of dipyridamole which prevents the entry of deoxycoformycin as well as adenosine into the cells in the Na+-free medium. These results further support the view that this is an ectoenzyme activity. The kinetics active adenosine transport were Km = 7.8 ± 1.1 μM with Vmax = 8.2 ± 2.8 μM/s in a Na+ medium and much less efficiently in a Li+ medium (Km= 250 ± 50 μM, Vmax = 7.8 ± 1.3 μM/s). Inhibition of adenosine transport by other nucleosides suggest a single Na+-dependent nucleoside transport system in murine splenocytes with narrow substrate specificity.||Source Title:||In Vivo||URI:||http://scholarbank.nus.edu.sg/handle/10635/107481||ISSN:||0258851X|
|Appears in Collections:||Staff Publications|
Show full item record
Files in This Item:
There are no files associated with this item.
checked on May 18, 2019
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.