Ballerini P, Ciccarelli R, Di Iorio P, Giuliani P, Caciagli F
Institute of Pharmacology and Bio-Medical Technologies, School of Medicine, University of Chieti, Italy.
Neurochem Res. 1995 Jun;20(6):697-704. doi: 10.1007/BF01705538.
[3H]Purine release from rat striatum astrocyte cultures was studied at 14 days in vitro (DIV). Superfusion of cultures with a Ca(2+)-free medium + 0.5 mM ethylene glycol-bis(beta-aminoethylether)N,N,N',N'-tetracetic acid (EGTA) reduced the electrically evoked [3H]purine release. Nimodipine only at the concentration of 10 microM modified [3H]purine outflow whereas 0.1 microM omega-conotoxin and 0.03-0.1 microM nitrendipine reduced the evoked one. Superfusion of cultures with 0.1 microM omega-conotoxin + 0.1 microM nitrendipine antagonized the evoked [3H]purine release similarly to each drug given alone. Neither nitrendipine nor omega-conotoxin influenced the uptake of 45Ca2+ by the cultures. The treatment of cells with the Ca2+ agonist Bay K 8644 did not affect [3H]purine release or the 45Ca2+ uptake. The drug did not either alter [Ca2+]i, evaluated by loading the cells with 3 microM Fura-2/AM. 10-30 microM 3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester (TMB-8), a blocker of intracellular Ca2+ discharge, significantly reduced the evoked [3H]purine release. On the other hand, 2 microM thapsigargin, an inhibitor of the ion store Ca2+ ATPase, was able to increase either the culture [3H]purine release or the [Ca2+]i. Together, the findings indicate that voltage-sensitive calcium channels (VSCCs) of the neuronal N and L-types are not involved in the modulation of [3H]purine release from rat cultured astrocytes whereas Ca2+ coming from intracytoplasmic stores seems to play a prevailing role. Moreover, agents which block VSCC, seem to be able to affect [3H]purine outflow with mechanisms other than VSCC gating.
在体外培养14天（DIV）时，研究了[3H]嘌呤从大鼠纹状体星形胶质细胞培养物中的释放情况。用无钙培养基 + 0.5 mM乙二醇双（β-氨基乙基醚）N，N，N'，N'-四乙酸（EGTA）对培养物进行灌流可减少电诱发的[3H]嘌呤释放。仅10 μM浓度的尼莫地平改变了[3H]嘌呤流出，而0.1 μM的ω-芋螺毒素和0.03 - 0.1 μM的尼群地平则减少了诱发的[3H]嘌呤释放。用0.1 μM的ω-芋螺毒素 + 0.1 μM的尼群地平对培养物进行灌流，与单独给予每种药物类似，拮抗了诱发的[3H]嘌呤释放。尼群地平和ω-芋螺毒素均未影响培养物对45Ca2+的摄取。用Ca2+激动剂Bay K 8644处理细胞不影响[3H]嘌呤释放或45Ca2+摄取。该药物也未改变通过用3 μM Fura-2/AM加载细胞评估的[Ca2+]i。10 - 30 μM的3,4,5-三甲氧基苯甲酸8-（二乙氨基）辛酯（TMB-8），一种细胞内Ca2+释放的阻滞剂，显著降低了诱发的[3H]嘌呤释放。另一方面，2 μM的毒胡萝卜素，一种离子储存Ca2+ ATP酶的抑制剂，能够增加培养物的[3H]嘌呤释放或[Ca2+]i。总之，这些发现表明神经元N型和L型电压敏感性钙通道（VSCCs）不参与调节大鼠培养星形胶质细胞中[3H]嘌呤的释放，而来自细胞质储存的Ca2+似乎起主要作用。此外，阻断VSCC的药物似乎能够通过VSCC门控以外的机制影响[3H]嘌呤流出。
