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2-Chloroadenosine, a permeant for the nucleoside transporter.
Biochemical Pharmacology
|September 15, 1985
Summary
Human erythrocytes transport 2-chloroadenosine via the nucleoside carrier, similar to other nucleosides. This finding suggests a reevaluation of why nucleoside transport inhibitors do not enhance 2-chloroadenosine
Area of Science:
- Biochemistry
- Cell Biology
- Pharmacology
Background:
- Erythrocytes possess specific transport mechanisms for nucleosides.
- The transport of nucleoside analogs like 2-chloroadenosine is not fully understood.
- Previous studies indicated a lack of saturable transport for nucleosides in dog erythrocytes.
Purpose of the Study:
- To investigate the uptake mechanism of 2-chloroadenosine in human erythrocytes.
- To compare 2-chloroadenosine transport in human versus dog erythrocytes.
- To determine if 2-chloroadenosine utilizes the same nucleoside carrier system.
Main Methods:
- Measurement of 2-chloroadenosine uptake in human and dog erythrocytes.
- Inhibition studies using nitrobenzylthioinosine (NBMPR), uridine, and adenosine.
- Analysis of countertransport effects between 2-chloroadenosine and uridine.
- Competitive inhibition assays for uridine influx and NBMPR binding.
Main Results:
- Human erythrocytes exhibit saturable 2-chloroadenosine uptake, inhibited by NBMPR, uridine, and adenosine.
- 2-Chloroadenosine competitively inhibits uridine influx and NBMPR binding in human erythrocytes.
- Dog erythrocytes show slow, linear 2-chloroadenosine uptake unaffected by NBMPR, confirming lack of a nucleoside carrier.
Conclusions:
- 2-Chloroadenosine enters human erythrocytes via the common nucleoside carrier system.
- The transport characteristics in human erythrocytes differ significantly from dog erythrocytes.
- Reassessment of the role of the nucleoside carrier in the pharmacological effects of 2-chloroadenosine is warranted.