| 15275960 |
Liu T, Fujita T, Kawasaki Y, Kumamoto E: Regulation by equilibrative nucleoside transporter of adenosine outward currents in adult rat spinal dorsal horn neurons. Brain Res Bull. 2004 Jul 30;64(1):75-83.
A current response induced by superfusing adenosine was examined in substantia gelatinosa (SG) neurons of adult rat spinal cord slices by using the whole-cell patch-clamp technique. In 78% of the neurons examined, adenosine induced an outward current at -70 mV [18.8 +/- 1.1 pA (n = 98) at 1mM] in a dose-dependent manner (EC (50) = 177 microM). A similar current was induced by A (1) agonist N (6)-cyclopentyladenosine (1 microM), whereas A (1) antagonist 8-cyclopentyl-1,3-dipropylxanthine (1 microM) reversed the adenosine action. The adenosine current reversed its polarity at a potential being close to the equilibrium potential for K (+), and was attenuated by Ba (2+) (100 microM) and 4-aminopyridine (5mM) but not tetraethylammonium (5mM). The adenosine current was enhanced in duration by equilibrative nucleoside-transport (rENT1) inhibitor S-(4-nitrobenzyl)-6-thioinosine (1 microM) and adenosine deaminase (ADA) inhibitor erythro-9-(2-hydroxy-3-nonyl) adenine (1 microM), and slowed in falling phase by adenosine kinase (AK) inhibitor iodotubercidine (1 microM). We conclude that a Ba (2+)- and 4-aminopyridine-sensitive K (+) channel in SG neurons is opened via the activation of A (1) receptors by adenosine whose level is possibly regulated by rENT1, adenosine deaminase and adenosine kinase. Considering that intrathecally-administered adenosine analogues produce antinociception, the regulatory systems of adenosine may serve as targets for antinociceptive drugs. |
82(1,1,1,2) |