CA HOMEOSTASIS--HORMONE SENSITIVE CA CHANNELS

众所周知，在不同的组织中，二氢吡啶结合在 纳摩尔浓度位于受体上方，能够阻断电压- 操纵钙离子通道。这些频道被称为L式的 钙离子通道。电压激活的钙通道打开、关闭或关门 根据跨膜调节的分子转移率 电压。然而，这些通道在几种类型的非 但电压门控钙离子内流在心肌细胞中的生理作用 这些细胞还没有被很好地理解。除L外的钙离子 通道、n、P和T型钙通道也已在 文学。然而，在我们报道之前，没有一个被描述为 对“类固醇敏感”。 这项提议的长期目标是确定L式的存在 钙通道α、亚单位转录本及其对细胞的依赖性 哈德氏腺组织匀浆中的类固醇和睾丸素。基于已发布的 C DNA序列，我们设计了针对两个高度保守的 所有已知钙通道共有的第四结构域的区域(S5-S6) MRNAs。我们将使用RT-PCR来扩增这些钙离子通道的mRNAs。Ca2+ 通过聚合酶链式反应的Southern分析对通道基因进行检测和定量 并通过Northern分析进行了验证。使用这种方法，我们将 建立基因组/非基因组类固醇转录调控 L型钙通道。我们的短期目标是从动力学角度描述 对睾酮敏感的高亲和力二氢吡啶受体 关于使用两个额外的二氢吡啶的饱和等温线(即， 尼莫地平和PN200-110)、钙离子对配体结合的依赖作用 已知的钙通道阻滞剂(如维拉帕米和地尔硫卓)，以及 α1，二氢吡啶结合亚基的大小。 类固醇激素作用的经典机制包括荷尔蒙进入 进入荷尔蒙结合并诱导构象变化的细胞 在其高亲和力的同源胞内受体蛋白。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激素能发挥其某些功能。 通过非基因组机制产生的电生理和行为效应。 这构成了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.