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Physiological and Pharmacological Roles of Vascular Nucleoside Transporters.
MedLine Citation:
PMID:  21266914     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Adenosine modulates various vascular functions such as vasodilatation and anti-inflammation. The local concentration of adenosine in the vicinity of adenosine receptors is fine-tuned by two classes of nucleoside transporters: equilibrative nucleoside transporters (ENTs) and concentrative nucleoside transporters (CNTs). In vascular smooth muscle cells, 95% of adenosine transport is mediated by ENT-1 and the rest by ENT-2. In endothelial cells, 60%, 10% and 30% of adenosine transport are mediated by ENT-1, ENT-2 and CNT-2, respectively. In-vitro studies show that glucose per se increases the expression level of ENT-1 via mitogen-activating protein kinase-dependent pathways. Similar results have been demonstrated in diabetic animal models. Hypertension is associated with the increased expression of CNT-2. It has been speculated that the increase in the activities of ENT-1 and CNT-2 may reduce the availability of adenosine to adenosine receptors, thereby weakening the vascular functions of adenosine. It may explain why patients with diabetes and hypertension suffer greater morbidity from ischemia and atherosclerosis. No oral hypoglycemic agents can inhibit ENTs, but an exception is troglitazone (a thiazolidinedione which has been withdrawn from the market). ENTs are also sensitive to dihydropyridine-type calcium-channel blockers, particularly nimodipine, which can inhibit ENT-1 in the nanomolar range. Those calcium-channel blockers are non-competitive inhibitors of ENTs, probably working through the reversible interactions with allosteric sites. The non-steroidal anti-inflammatory drug sulindac sulfide is a competitive inhibitor of ENT-1. In addition to their original pharmacological actions, it is believed that the drugs mentioned above may regulate vascular functions through potentiation of the effects of adenosine.
Authors:
Rachel W S Li; Cui Yang; Albert S M Sit; Sophie Y T Lin; Eva Y W Ho; George P H Leung
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-1-22
Journal Detail:
Title:  Journal of cardiovascular pharmacology     Volume:  -     ISSN:  1533-4023     ISO Abbreviation:  -     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2011-1-26     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7902492     Medline TA:  J Cardiovasc Pharmacol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Department of Pharmacology and Pharmacy, The University of Hong Kong.
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