Direct interference of HIV protease inhibitors with pancreatic β-cell function
Direct interference of HIV protease inhibitors with pancreatic β-cell function
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DOI：
10.1007/s00210-004-0933-6
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发表时间：
2004-06-01
影响因子：
3.6
通讯作者：
Drews, G
中科院分区：
文献类型：
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作者：
Düfer, M;Neye, Y;Drews, G
本研究的目的是评估 HIV 蛋白酶抑制剂是否直接干扰胰腺 P 细胞的刺激-分泌耦合。通过放射免疫测定 (RIA)、荧光染料 fura-2 的胞质游离 Ca2+ 浓度 ([Ca2+](c)) 以及膜片钳技术的全细胞膜电流测定胰岛素分泌。利托那韦和奈非那韦以浓度依赖性方式抑制葡萄糖诱导的胰岛素分泌，但茚地那韦则不然。在存在刺激性葡萄糖浓度的情况下，利托那韦和奈非那韦可降低 [Ca2+](c)，而茚地那韦同样没有效果。利托那韦和奈非那韦完全抑制甲苯磺丁脲的作用，甲苯磺丁脲通常通过阻断 K-ATP 通道来增加 [Ca2+](c)。这一观察表明两种药物对 K-ATP 通道有作用，或者在刺激-分泌耦合中远离这些通道。利托那韦用于进一步评估 HIV 蛋白酶抑制剂对 β 细胞离子通道电流的直接影响。出乎意料的是，利托那韦既不抑制全细胞K-ATP电流，也不抑制全细胞L-型Ca2+电流。在利托那韦存在的情况下，甲苯磺丁脲几乎完全抑制 K-ATP 电流，但利托那韦不改变 K-ATP 通道的甲苯磺丁脲敏感性。利托那韦增加了葡萄糖诱导的动作电位的长度并降低了频率。这种效应可归因于电压依赖性 K+ 电流的抑制。细胞内储存似乎不参与利托那韦诱导的 [Ca2+](c) 降低。 总之，不同的 HIV 蛋白酶抑制剂令人惊讶地揭示了对胰岛素分泌的不同影响。利托那韦通过降低 [Ca2+](c) 来抑制胰岛素分泌，但这种作用显然与 K-ATP 通道的开放或电压依赖性 Ca2+ 通道的关闭无关，这些通道通常被认为在刺激-分泌耦合中发挥关键作用。
The aim of the present study was to evaluate whether HIV protease inhibitors directly interfere with stimulus-secretion coupling in pancreatic P-cells. Insulin secretion was determined by a radioimmunoassay (RIA), cytosolic free Ca2+ concentration ([Ca2+](c)) with the fluorescence dye fura-2 and whole-cell membrane currents with the patch-clamp technique.Glucose-induced insulin secretion was inhibited in a concentration-dependent manner by ritonavir and nelfinavir but not by indinavir. Ritonavir and nelfinavir lowered [Ca2+](c) in the presence of a stimulatory glucose concentration whereas indinavir again had no effect. Ritonavir and nelfinavir completely inhibited the effect of tolbutamide, which normally increases [Ca2+](c) by blocking K-ATP channels. This observation points to an action of both drugs on K-ATP channels or a step distal to these channels in stimulus-secretion coupling. Ritonavir was used to further evaluate the direct effects of HIV protease inhibitors on beta-cell ion channel currents. Unexpectedly, ritonavir inhibited neither the whole-cell K-ATP current nor the whole-cell L-type Ca2+ current. Tolbutamide almost completely suppressed the K-ATP current in the presence of ritonavir excluding that ritonavir alters the tolbutamide sensitivity of the K-ATP channel. Ritonavir increased the length and decreased the frequency of glucose-induced action potentials. This effect can be attributed to inhibition of voltage-dependent K+ currents. Intracellular stores seem not to be involved in the ritonavir-induced lowering of [Ca2+](c).In conclusion, different HIV protease inhibitors surprisingly reveal distinct effects on insulin secretion. Ritonavir inhibits insulin secretion by lowering [Ca2+](c) but this effect is evidently independent of the opening o K-ATP channels or the closure of voltage-dependent Ca2+ channels, which are commonly considered to play a key role in stimulus-secretion coupling.