Latini S, Pedata F, Pepeu G
Department of Preclinical and Clinical Pharmacology, University of Florence, Italy.
Naunyn Schmiedebergs Arch Pharmacol. 1997 Feb;355(2):250-5. doi: 10.1007/pl00004939.
The role of L-, N- and P-type voltage-dependent calcium channels (VDCCs) in the release of adenosine from rat hippocampal slices was investigated by evaluating the effect of the L-channel activator 1,4-dihydro-2,6-dimethyl-5-nitro-4-[2-(trifluoromethyl)-phenyl]-3-pyr idi ne carboxylic acid methyl ester (Bay K 8644) and of three calcium channel antagonists: the L-channel antagonist nifedipine, the N-channel blocker omega-conotoxin GVIA (omega-CgTx) and the P-channel blocker omega-agatoxin IVA (omega-Aga-IVA). Adenosine and inosine release, evoked by 5 min electrical stimulation at 10 Hz of hippocampal slices, was assayed by HPLC with ultraviolet absorbance or fluorimetric detection. Nifedipine (100 nM) did not affect adenosine and inosine release evoked by electrical stimulation. Bay K 8644 (100 nM) brought about a statistically significant increase in adenosine evoked release (70%). At a higher concentration (1 microM) Bay K 8644 had no significant effect either on adenosine or inosine release evoked by electrical stimulation. The increase in adenosine release elicited by 100 nM Bay K 8644 was abolished by nifedipine (100 nM). Both omega-CgTx (10 microM) and omega-Aga-IVA (200 nM) caused a statistically significant reduction (77-78%) in evoked release of adenosine. When the previously demonstrated glutamate-dependent component of the release of adenosine was suppressed in the presence of the NMDA and non-NMDA receptor antagonists, D(-)-2-amino-7-phosphonoheptanoic acid (D-AP7. 100 microM) and 6,7-dinitroquinoxaline-2,3-dione (DNQX, 10 microM), the remaining release of adenosine was again significantly reduced by omega-CgTx (10 microM) (60%) and omega-Aga-IVA (200 nM) (73%). These data suggest that, while L-type VDCCs are involved in the regulation of the evoked release of adenosine only when activated by Bay K 8644, both P- and N-channels play a direct role in the calcium entry involved in the coupling process between electrical stimulation and adenosine release.
通过评估L型通道激活剂1,4-二氢-2,6-二甲基-5-硝基-4-[2-(三氟甲基)-苯基]-3-吡啶羧酸甲酯（Bay K 8644）以及三种钙通道拮抗剂的作用，研究了L型、N型和P型电压依赖性钙通道（VDCCs）在大鼠海马切片中腺苷释放过程中的作用。这三种钙通道拮抗剂分别是：L型通道拮抗剂硝苯地平、N型通道阻滞剂ω-芋螺毒素GVIA（ω-CgTx）和P型通道阻滞剂ω-阿加毒素IVA（ω-Aga-IVA）。通过高效液相色谱法结合紫外吸收或荧光检测，测定了在10 Hz频率下对海马切片进行5分钟电刺激所诱发的腺苷和肌苷释放量。硝苯地平（100 nM）不影响电刺激诱发的腺苷和肌苷释放。Bay K 8644（100 nM）使腺苷诱发释放量出现具有统计学意义的增加（70%）。在更高浓度（1 μM）时，Bay K 8644对电刺激诱发的腺苷或肌苷释放均无显著影响。100 nM Bay K 8644所引发的腺苷释放增加被硝苯地平（100 nM）消除。ω-芋螺毒素GVIA（10 μM）和ω-阿加毒素IVA（200 nM）均使诱发的腺苷释放量出现具有统计学意义的减少（77 - 78%）。当在NMDA和非NMDA受体拮抗剂D-(-)-2-氨基-7-膦酰庚酸（D-AP7，100 μM）和6,7-二硝基喹喔啉-2,3-二酮（DNQX，10 μM）存在的情况下，抑制先前已证实的腺苷释放中谷氨酸依赖性成分时，ω-芋螺毒素GVIA（10 μM）（60%）和ω-阿加毒素IVA（200 nM）（73%）再次使剩余的腺苷释放量显著减少。这些数据表明，虽然L型VDCCs仅在被Bay K 8644激活时参与诱发的腺苷释放调节，但P型和N型通道在电刺激与腺苷释放之间耦合过程中涉及的钙内流中均发挥直接作用。
