Pilitsis J G, Kimelberg H K
Division of Neurosurgery, A-60, Department of Pharmacology and Neuroscience, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA.
Brain Res. 1998 Jul 6;798(1-2):294-303. doi: 10.1016/s0006-8993(98)00430-2.
The characteristics of adenosine receptors found in glial fibrillary acid protein (GFAP)-positive astrocytes acutely isolated from the cerebral cortices of 4- to 12-day old rats were examined by evaluating the effects of adenosine and its analogues on intracellular calcium levels. First, these effects were compared with those seen in primary astrocytic cultures, and it was found that acutely isolated astrocytes showed much greater sensitivity to adenosine than their cultured counterparts. Then, the adenosine evoked calcium responses in acutely isolated cells were evaluated under various conditions. The responses to adenosine were not inhibited by papaverine, an uptake blocker, or by removal of extracellular calcium. U73122, a phospholipase C inhibitor, was able to completely inhibit the adenosine response. The receptor inhibitor 3-isobutyl-1-methylxanthine inhibited the calcium response to adenosine, providing evidence that the response is not coupled to the xanthine-insensitive A3 receptor. The stimulatory action of NECA, a non-selective analogue, was blocked neither by the A2A-selective receptor antagonist 8-(3-chlorostyryl) caffeine nor by the A1-selective receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine. The A2B receptor antagonist alloxazine, however, was able to completely inhibit the increase in intracellular calcium produced by NECA. Taken together, these data suggest that the adenosine-evoked calcium response in acutely isolated astrocytes is coupled to the A2B receptor.
通过评估腺苷及其类似物对细胞内钙水平的影响，研究了从4至12日龄大鼠大脑皮质急性分离出的胶质纤维酸性蛋白（GFAP）阳性星形胶质细胞中腺苷受体的特征。首先，将这些影响与原代星形胶质细胞培养物中的影响进行比较，发现急性分离的星形胶质细胞对腺苷的敏感性远高于其培养的对应物。然后，在各种条件下评估急性分离细胞中腺苷诱发的钙反应。对腺苷的反应不受摄取阻滞剂罂粟碱或去除细胞外钙的抑制。磷脂酶C抑制剂U73122能够完全抑制腺苷反应。受体抑制剂3-异丁基-1-甲基黄嘌呤抑制了对腺苷的钙反应，这表明该反应与对黄嘌呤不敏感的A3受体无关。非选择性类似物NECA的刺激作用既不受A2A选择性受体拮抗剂8-（3-氯苯乙烯基）咖啡因的阻断，也不受A1选择性受体拮抗剂8-环戊基-1,3-二丙基黄嘌呤的阻断。然而，A2B受体拮抗剂别嘌呤能够完全抑制NECA产生的细胞内钙增加。综上所述，这些数据表明急性分离的星形胶质细胞中腺苷诱发的钙反应与A2B受体有关。
