CA HOMEOSTASIS--HORMONE SENSITIVE CA CHANNELS

众所周知，在不同的组织中，二氢吡啶结合在 纳摩尔浓度高于受体，能够阻断电压， 操作的Ca 2+通道。 这些通道被称为L型 Ca 2+通道 电压激活的Ca 2+通道打开和关闭，或门 根据由跨膜调节的分子转换速率， 电压. 然而，这些渠道被发现在几种类型的非- 可兴奋的细胞，但电压门控Ca 2+进入的生理作用， 这些细胞还不太清楚。 除了L型Ca 2 + 通道、n型、P型和T型Ca 2+通道也已在文献中描述。 文学 然而，在我们报告之前，没有人被描述为 对类固醇敏感 该提案的长期目标是确定L型的存在 Ca 2+通道α、亚基转录本及其对细胞内Ca 2+浓度的依赖性 哈氏腺匀浆中的类固醇、睾酮。 根据公布的 cDNA序列，我们设计了两个高度保守的PCR引物， 所有已知Ca 2+通道共有的第四结构域的区域（S5-S6） mRNA。 我们将使用RT-PCR扩增这些Ca 2+通道mRNA。 Ca2+ 通过PCR的Southern分析检测和定量通道mRNA 产品并经北方分析验证。 通过这种方法，我们将 建立基因组/非基因组类固醇转录控制的 L型钙通道。 我们的短期目标是从动力学上表征 睾酮敏感的高亲和力二氢吡啶受体， 关于使用两种另外的二氢吡啶的饱和等温线（即， 尼莫地平和PN 200 -110），配体结合的Ca 2+依赖性，效果 已知的Ca 2+通道阻断剂（例如，维拉帕米和地尔硫卓）， α 1二氢吡啶结合亚基的大小。 类固醇激素作用的经典机制涉及激素的进入 激素与细胞结合并引起构象变化 在其高亲和力同源细胞内受体蛋白中。 这些事件 被认为完全依赖于激素结合。 最近， 已知性腺和肾上腺类固醇可以发挥它们的一些作用， 通过非基因组机制的电生理和行为效应。 这是一个新兴但有争议的概念， 神经内分泌学

It is well known that in different tissues, dihydropyridines bind at nanomolar concentrations top a receptor and are able to block voltage- operated Ca2+ channels. These channels have been referred to as L-type Ca2+ channels. Voltage-activated Ca2+ channels open, and close, or gate according to molecular transition rates that are regulated by transmembrane voltage. However, these channels are found in several types of non- excitable cells but the physiological role of voltage-gated Ca2+ entry in these cells is not well understood. In addition to the L-type Ca2+ channel, n, P, and T-type Ca2+ channels have also been described in the literature. However, prior to our reporting none have been described as being "steroid sensitive". The long term goal of this proposal is to determine the presence of L-type Ca2+ channel alpha, subunit transcripts and their dependence upon the steroid, testosterone in Harderian gland homogenates. Based upon published cDNA sequences, we have designed PCR primers to two highly conserved regions (S5-S6) of the fourth domain common to all known Ca2+ channel mRNAs. We will use RT-PCR to amplify these Ca2+ channel mRNAs. Ca2+ channel mRNA will be detected and quantitated by Southern analysis of PCR products and verified by Northern analysis. Using this approach, we will establish the genomic/nongenomic steroidal transcriptional control of the L-type Ca2+ channel. Our short term goal is to kinetically characterize the testosterone sensitive, high affinity dihydropyridine receptor with regard to saturation isotherms using two additional dihydropyridines (i.e., nimodipine and PN200-110), Ca2+ dependence of ligand binding, the effects of known Ca2+ channel blockers (e.g., verapamil and diltiazem), and the size of the alpha1, dihydropyridine binding subunit. The classical mechanism of steroid hormone action involves entry of hormone into a cell where the hormone binds to and induces a conformational change in its high affinity cognate intracellular receptor protein. These events are believed to be dependent exclusively on hormone binding. Recently, gonadal and adrenal steroids have been known to exert some of their electrophysiological and behavioral effects through non-genomic mechanisms. This constitutes an emerging but controversial concept in neuroendocrinology.