MECHANISMS OF HORMONE AND TRANSMITTER SECRETION

我们的工作继续集中在导致融合的过程中， 颗粒和质膜在胞吐作用，包括 嗜铬细胞，胰岛β细胞，神经末梢，和 分泌粘蛋白的人结肠癌细胞。 接触与融合事件 在胞吐作用期间，可以由蛋白质突触蛋白控制。 我们有 最近克隆并测序了该蛋白的cDNA，并了解到 它是膜联蛋白基因家族的一员。 我们已经表达了突触蛋白 在大肠大肠杆菌中表达融合蛋白， 和信道特性。 分泌机制也已研究， 完整的嗜铬细胞，其中有证据表明， 钙和钡通过不同的机制促进分泌的概念。 嗜铬细胞中的乙酰胆碱受体被发现是 不同于经典的烟碱受体，因为它具有 出乎意料的毒蕈碱特性 一种新的钙通道已经被发现， 在人类β细胞中发现，它对葡萄糖和相关的 代谢物。 这种通道被我们命名为“G型”钙通道， 可能在胰岛葡萄糖激活中起核心作用。 葡萄糖诱导 胰岛素的释放受乙酰胆碱的调节，药理学分析 表明毒蕈碱受体类型是M1而不是M2。 的 肾上腺髓质提供了一个易处理的系统来研究 内分泌细胞和粘附的毛细血管之间。 内皮细胞具有 MAO-A，排他地，和各种类固醇影响这种酶的表达， 而不影响仅在嗜铬细胞中发现的MAO-B。 高效液相色谱库仑法测定抗坏血酸的新方法 已经开发了电化学检测。 该方法允许 维生素的测量，不仅在细胞，如白细胞， 嗜铬细胞，还有人血浆。 抗坏血酸的两种转运蛋白 在人类嗜中性粒细胞中检测到酸。 毫摩尔浓度的 在两种人中性粒细胞中都检测到了未结合形式的抗坏血酸 和单核细胞。

Our work continues to focus on the processes leading to fusion between granule and plasma membranes during exocytosis in cells, including chromaffin cells, beta cells from islet of Langerhans, nerve terminals, and mucin secreting human colon carcinoma cells. The contact and fusion event during exocytosis may be controlled by the protein synexin. We have recently cloned and sequenced the cDNA for this by the protein, and learned that it is a member of the annexin gene family. We have expressed synexin in E. coli and have found the recombinant protein to express both fusion and channel properties. Secretion mechanisms have also been studied in intact chromaffin cells, in which evidence has been found to support the concept that calcium and barium promote secretion by separate mechanisms. The acetycholine receptor in chromaffin cells has been found to be different from the classical nicotinic receptor, inasmuch as it has unexpected muscarinic character. A novel calcium channel has been discovered in human beta cells, which responds to glucose and related metabolites. This channel is named by us the "G-type" calcium channel, and may play a central role in glucose activation if islets. Glucose induced insulin release is modulated by acetylcholine, and pharmacological analysis reveals that the muscarinic receptor type is M1 rather than M2. The adrenal medullas has provided a tractable system to study the interaction between endocrine cells and adherent capillaries. Endothelial cells have MAO-A, exclusively, and various steroids affect expression of this enzyme, without affecting the MAO-B which is exclusively found in chromaffin cells. A new method for measuring ascorbic acid using HPLC and coulometric electrochemical detection has been developed. The method allows measurement of the vitamin, not only in cells such as leucocytes and chromaffin cells, but also human plasma. Two transporters for ascorbic acid have been detected in human neutrophils. Millimolar concentrations of ascorbic acid have been detected in unbound form in both human neutrophils and monocytes.