Merlo D, Volonté C
Institute of Neurobiology, C.N.R. Viale Marx, Rome, Italy.
Biochem Biophys Res Commun. 1996 Aug 23;225(3):907-14. doi: 10.1006/bbrc.1996.1271.
Selected purinoceptor modulators were previously shown to prevent glutamate-evoked cytotoxicity in cerebellar granule neurons. In the same cellular system, we now identify and characterize the presence of P2 receptors. The binding of [3H]ATP to membranes of cerebellar granule neurons grows monotonically as a function of neuronal differentiation, is saturable and reaches steady state within 6 min. Scatchard plot of the equilibrium saturation data is curvilinear with a Kd value of 28 nM and a Bmax value of 87 pmol/ mg of protein for the high affinity binding sites and a Kd value of 1.5 microM and Bmax value of 1.2 nmol/mg of protein, for the more numerous low affinity binding sites. We also show that extracellular ATP increases the release, but not the uptake, of [3H]D-aspartate and that it furthermore potentiates the release of [3H]D-aspartate evoked by glutamate and KCI. ATP itself is released by cerebellar granule cultures and such release grows monotonically as a function of neuronal differentiation. These data are consistent with the role that ATP is believed to play as a cotransmitter for the central nervous system.
先前的研究表明，某些嘌呤受体调节剂可预防谷氨酸诱发的小脑颗粒神经元细胞毒性。在同一细胞系统中，我们现在鉴定并表征了P2受体的存在。[3H]ATP与小脑颗粒神经元细胞膜的结合随神经元分化呈单调增长，具有饱和性且在6分钟内达到稳态。平衡饱和数据的Scatchard图呈曲线，高亲和力结合位点的Kd值为28 nM，Bmax值为87 pmol/mg蛋白质；对于数量更多的低亲和力结合位点，Kd值为1.5 μM，Bmax值为1.2 nmol/mg蛋白质。我们还表明，细胞外ATP增加了[3H]D-天冬氨酸的释放，但不影响其摄取，并且它还增强了谷氨酸和氯化钾诱发的[3H]D-天冬氨酸的释放。ATP本身可由小脑颗粒培养物释放，且这种释放随神经元分化呈单调增长。这些数据与ATP被认为作为中枢神经系统共递质所起的作用一致。
