兰尼碱受体拮抗剂对阴茎海绵体平滑肌细胞钙离子浓度的影响

The erection of penis is affected by the concentration of cellular calcium ion of smooth muscle in the corpus cavernosum. The current studies have demonstrated that penile teleneuron releases NO,which enters into smooth muscle cells to activate guanylate cyclase (GC). This enzyme catalyzes the transformation of guanosine triphosphate to cyclic guanosine monophosphate, causing the reduction of cellular calcium, which induces the relaxation of penile smooth muscle,and the erection of penis. The concentration of cellular calcium is regulated by voltage-dependent calcium channel, receptor-operated calcium channel, inositol triphosphate system, and ryanodine receptor system. However, it is still unclear which calcium regulation pathway is employed by cyclic guanosine monophosphate to induce the reduction of smooth muscle cellular calcium, and what is the mechanism. In the resting state, the concentration of intracellular calcium is about 1/20,000 of that of extra-cellular calcium. In the affective state, the concentration of intracellular calcium increases through dual mechansims: release from intracellular calcium pool and influx of extracellular calcium. Calcium release from intracelluar calcium pool, which is able to raise the intracellular calcium concentration to the peak rapidly, is regulated by inositol triphosphate system and ryanodine receptor system with distinct calcium signals. Ryanodine receptors discharge calcium sparks, inducing membrane hperpolarization, which inhibits L-type calcium channel and further reduces the calcium influx, causing relaxation of smooth muscle. In this project, we plan to investigate the effects of the antagonist of ryanodine receptor on penile smooth muscle and its mechanism.

ED是成年男性常见病。目前治疗ED的PDE5抑制剂副作用较大，部分病人使用受限。研究表明神经末梢释放NO通过胞膜进入平滑肌细胞内，激活鸟苷酸环化酶，使三磷酸鸟苷转化为cGMP，引起细胞内钙离子减少，导致平滑肌舒张，阴茎勃起。平滑肌细胞内钙离子受电压依赖性钙通道、受体操纵性钙通道、三磷酸肌醇系统和兰尼碱受体系统调节。cGMP究竟通过哪个钙离子调节途径引起海绵体平滑肌内钙内流减少的机制尚不清楚。静息状态下，细胞内钙约为细胞外钙离子浓度的1/20000。细胞内钙池有三磷酸肌醇和兰尼碱受体系统，功能迥异。有报道兰尼碱受体释放钙火花可诱导胞膜产生超极化,抑制L型钙通道, 使钙内流减少，引起心肌平滑肌细胞舒张。我们前期研究发现兰尼碱受体拮抗剂局部注射可以引起犬阴茎勃起。本工作拟研究兰尼碱受体拮抗剂引起阴茎勃起的机制。进一步开发新的治疗ED药物。

目的：研究兰尼碱受体拮抗剂对阴茎海绵体平滑肌细胞钙离子浓度的影响.方法：取32只雄性成年犬，分成丁卡因干预组、肝素干预组、万艾可干预组和对照组，采用ELISA法对海绵体血窦内和阴茎平滑肌匀浆组织分别进行钙离子浓度测定。.结果：丁卡因干预组（RyR抑制剂）：海绵体血窦Ca++浓度水平干预前和干预后自身比较，有显著性意义（p<0.05），阴茎明显勃起，硬度、长度和直径显著增加。阴茎组织匀浆液Ca++浓度水平干预后30分钟，比较无显著性意义（p=0.178>0.05）。.肝素干预组（IP3R抑制剂）：.海绵体血窦Ca++浓度水平干预前和干预后比较，有显著性意义（p=0.0011<0.05），阴茎明显勃起，硬度、长度和直径显著增加。阴茎组织匀浆液Ca++浓度水平：干预后30分钟，比较无显著性意义（p=0.412>0.05）。.万艾可干预组（5-型磷酸二酯酶抑制剂）：.海绵体血窦Ca++浓度水平:干预前和干预后比较，有显著性意义（p=0.0011<0.05），阴茎勃起明显，硬度、长度和直径显著增加。阴茎组织匀浆液Ca++浓度水平：干预后30分钟，无显著性意义（p=0.095>0.05）。.结论：.1.本组初步提示：RyR受到抑制或IP3R受到抑制时，阴茎明显勃起，硬度、长度和直径显著增加。匀浆组织中Ca++浓度无显著性变化，而海绵体血窦Ca++浓度显著性增加，推测是否存在细胞内RyR受到抑制时，Ip3R发挥调节机制，或IP3R受到抑制时，RyR发挥调节机制。进而调节阴茎平滑肌细胞内Ca++的流动，调节血窦内皮细胞Ca++的流动，引起阴茎勃起。.2.本组初步提示：万艾可干预后，阴茎明显勃起，硬度、长度和直径显著增加。匀浆组织中Ca++浓度无显著性变化，而海绵体血窦Ca++浓度显著性增加。推测：加入万艾可干预后，万艾可作为5-型磷酸二酯酶的抑制剂，在影响调节Ca++流动的同时是否存在影响RyR钙火花和IP3R的调节机制呢？