Nah S Y, Unteutsch A, Bunzow J R, Cook S P, Beacham D W, Grandy D K
Department of Physiology, School of Veterinary Medicine, Chonnam National University, Kwangju, South Korea.
Brain Res. 1997 Aug 22;766(1-2):66-71. doi: 10.1016/s0006-8993(97)00537-4.
Whole-cell patch-clamp recordings were used to study Ba2+ currents through voltage-dependent Ca2+ channels in dorsal root ganglion x mouse neuroblastoma hybrid (F-11) cells. Opioid agonists selective for either mu (Tyr-D-Ala-Gly-Mephe-Gly-ol; DAMGO) or delta (Tyr-D-Pen-Gly-Phe-D-Pen-OH; DPDPE) receptors inhibited high-threshold Ba2+ currents. The inhibition was reversible, naloxone-sensitive, and dose-dependent. The inhibitory effects of both DAMGO and DPDPE were blocked by pretreatment of the cells with pertussis toxin (PTX) as well as by brief exposure to the sulfhydryl alkylating agent, N-ethylmaleimide (NEM). The N-type Ca2+ channel antagonist omega-conotoxin GVIA (omega-CTX GVIA) irreversibly inhibited high threshold Ba2+ currents by 66% and blocked the inhibitory effect of DAMGO or DPDPE. In contrast, the L-type Ca2+ channel blocker nifedipine inhibited high threshold Ba2+ currents by 15% and failed to block the inhibitory effect of DAMGO or DPDPE. These results demonstrate that mu and delta opioid receptors are negatively coupled to N-type Ca2+ channels via PTX- and NEM-sensitive GTP-binding proteins in F-11 cells.
采用全细胞膜片钳记录技术，研究背根神经节x小鼠神经母细胞瘤杂交（F-11）细胞中通过电压依赖性钙通道的Ba2+电流。对μ（酪氨酰-D-丙氨酰-甘氨酰-甲硫氨酰-甘氨醇；DAMGO）或δ（酪氨酰-D-青霉胺-甘氨酰-苯丙氨酰-D-青霉胺；DPDPE）受体具有选择性的阿片类激动剂抑制高阈值Ba2+电流。这种抑制是可逆的、对纳洛酮敏感且呈剂量依赖性。DAMGO和DPDPE的抑制作用均被百日咳毒素（PTX）预处理细胞以及短暂暴露于巯基烷化剂N-乙基马来酰亚胺（NEM）所阻断。N型钙通道拮抗剂ω-芋螺毒素GVIA（ω-CTX GVIA）不可逆地抑制高阈值Ba2+电流66%，并阻断DAMGO或DPDPE的抑制作用。相比之下，L型钙通道阻滞剂硝苯地平抑制高阈值Ba2+电流15%，但未能阻断DAMGO或DPDPE的抑制作用。这些结果表明，在F-11细胞中，μ和δ阿片受体通过PTX和NEM敏感的GTP结合蛋白与N型钙通道负性偶联。
