Uptake of adenosine by isolated bovine cortex microvessels

Area of Science:

• Neuroscience
• Biochemistry
• Pharmacology

Background:

• Adenosine plays crucial roles in the central nervous system.
• Understanding adenosine transport is vital for studying brain function and drug delivery.

Purpose of the Study:

• To characterize the adenosine uptake system in bovine cortical microvessels.
• To investigate the affinity and sensitivity of this system to various inhibitors.

Main Methods:

• Isolation of microvessels from bovine cortex.
• Measurement of adenosine uptake kinetics (KM and Vmax).
• Assessment of inhibition by dipyridamole, papaverine, CuCl2, adenine nucleotides, and xanthine derivatives.

Main Results:

• High-affinity adenosine uptake observed with KM = 1.92 microM and Vmax = 1.93 pmol/mg protein/10 min.
• Uptake was significantly inhibited by dipyridamole, papaverine, CuCl2, and adenine nucleotides.
• Xanthine derivatives showed differential inhibition, with 3-methyl-1-(5'-oxohexyl)-7-propylxanthine being most potent, while theophylline stimulated uptake.

Conclusions:

• Bovine cortical microvessels possess a high-affinity nucleoside transport system for adenosine.
• This system shares characteristics with the blood-brain barrier's nucleoside transporter.
• Findings support the role of microvessels in regulating adenosine levels within the brain parenchyma.