背景:激活内皮小电导钙激活K+通道(KCa2.3)和中等电导钙激活K+通道(KCa3.1)导致血管舒张。我们发现海绵体中的内皮KCa2.3下调会降低勃起功能。
目的:我们假设在2型糖尿病小鼠中,勃起组织中KCa2.3和KCa1.1通道的功能受损。
方法:测量勃起功能,并安装海绵体条进行功能研究,并进行qPCR和免疫印迹处理。
结果:2型糖尿病对勃起功能的影响,钙激活钾通道的表达和功能。
结果:在麻醉的糖尿病db/db小鼠中,与非糖尿病杂合db/+小鼠相比,勃起功能明显下降,与正常的C57BL/6小鼠相比,损伤甚至更明显。qPCR显示db/db小鼠海绵体中KCa2.3和KCa1.1α通道表达上调。免疫印迹显示db/db小鼠海绵体中KCa2.3通道的下调。乙酰胆碱松弛受损,而一氧化氮诱导的松弛,与C57BL/6和db/+小鼠相比,db/db的供体SNP在海绵体中没有改变。阿帕明,KCa2通道的阻断剂,所有实验组均抑制海绵体的乙酰胆碱松弛。在阿帕明的存在下,db/db与C57BL/6和db/小鼠相比,海绵体中的乙酰胆碱松弛明显减少。KCa2和KCa3.1通道的开启器,NS309增强了db/+和db/db小鼠的海绵体中的乙酰胆碱松弛。伊比利亚毒素,KCa1.1通道的阻滞剂,抑制db/+小鼠海绵体乙酰胆碱松弛,而在db/db小鼠的组织中没有作用。
结论:与杂合和对照小鼠相比,糖尿病db/db小鼠的勃起功能受到严重影响,研究结果表明,非糖尿病db/+和糖尿病db/db小鼠可用于药物测试,分别,中度和重度勃起功能障碍。与C57BL/6小鼠相比,在存在阿帕明的情况下表达改变和乙酰胆碱松弛受损可能表明KCa1.1通道功能降低可能是糖尿病db/db小鼠内皮依赖性松弛和勃起功能障碍受损的基础。
■本研究提供了2型糖尿病小鼠模型,以测试中度和重度勃起功能障碍药物。降低KCa1.1通道功能有助于勃起功能障碍,并且电生理测量不支持它是一个限制。
结论:我们的结果表明,在海绵体中,伊贝毒素敏感的KCa1.1通道对松弛的贡献减少,而阿帕明敏感的KCa2.3通道出现上调。KCa1.1通道功能受损可能导致糖尿病db/db小鼠勃起功能受损。
Activation of endothelial small conductance calcium-activated K+ channels (KCa2.3) and intermediate conductance calcium-activated K+ channels (KCa3.1) leads to vascular relaxation. We found endothelial KCa2.3 down-regulation in the corpus cavernosum diminishes erectile function.
We hypothesized that in type-2 diabetic mice, the function of KCa2.3 and KCa1.1 channels is impaired in erectile tissue.
Erectile function was measured, and corpus cavernosum strips were mounted for functional studies and processed for qPCR and immunoblotting.
Effects of type 2 diabetes on erectile function, expression and function of calcium-activated potassium channels.
In anesthetized diabetic db/db mice, erectile function was markedly decreased compared to non-diabetic heterozygous db/+ mice, and the impairment was even more pronounced compared to normal C57BL/6 mice. qPCR revealed KCa2.3 and KCa1.1α channel expressions were upregulated in corpus cavernosum from db/db mice. Immunoblotting showed down-regulation of KCa2.3 channels in the corpus cavernosum from db/db mice. Acetylcholine relaxations were impaired while relaxations induced by the nitric oxide, donor SNP were unaltered in corpus cavernosum from db/db compared to C57BL/6 and db/+ mice.
Apamin, a blocker of KCa2 channels, inhibited acetylcholine relaxation in corpus cavernosum from all experimental groups. In the presence of
apamin, acetylcholine relaxation was markedly decreased in corpus cavernosum from db/db vs C57BL/6 and db/+ mice. An opener of KCa2 and KCa3.1 channels, NS309, potentiated acetylcholine relaxations in corpus cavernosum from db/+ and db/db mice. Iberiotoxin, a blocker of KCa1.1 channels, inhibited acetylcholine relaxation in corpus cavernosum from db/+ mice, while there was no effect in tissue from db/db mice.
Erectile function in diabetic db/db mice was severely affected compared to heterozygous and control mice, findings suggesting the non-diabetic db/+ and diabetic db/db mice for translational purpose can be used for drug testing on, respectively, moderate and severe erectile dysfunction. The altered expressions and impaired acetylcholine relaxation in the presence of
apamin compared to C57BL/6 mice may suggest decreased KCa1.1 channel function may underpin impaired endothelium-dependent relaxation and erectile dysfunction in diabetic db/db mice.
The present study provides a mouse model for type 2 diabetes to test moderate and severe erectile dysfunction drugs. Decreased KCa1.1 channel function contributes to erectile dysfunction, and it is a limitation that it is not supported by electrophysiological measurements.
Our results suggest that the contribution of iberiotoxin-sensitive KCa1.1 channels to relaxation is reduced in the corpus cavernosum, while
apamin-sensitive KCa2.3 channels appear upregulated. The impaired KCa1.1 channel function may contribute to the impaired erectile function in diabetic db/db mice.