Whim Matthew D
Department of Biology, Pennsylvania State University, State College, Pennsylvania 16802, USA.
J Neurosci. 2006 Jun 14;26(24):6637-42. doi: 10.1523/JNEUROSCI.5100-05.2006.
Adrenal chromaffin cells are an important part of the neuroendocrine system and under stressful conditions release catecholamines into the blood, thus regulating many physiological processes. In addition to the catecholamines, chromaffin cells also synthesize a range of peptides, including neuropeptide Y. Although the catecholamines and peptides are both contained within dense core granules, whether they are copackaged is less clear. Here, I investigate whether a single dense core granule can be loaded with both types of transmitter molecules. Using amperometry and FMRFamide tagging, I simultaneously measure the secretion of the catecholamines and a neuropeptide from mouse chromaffin cells in vitro. I find that fusion of a single dense core granule releases both types of transmitters into the extracellular space. Significant amounts of peptide escape from a fusing granule in 1-2 ms: almost as rapidly as the catecholamines. This suggests that the kinetics of peptide secretion might not be as sluggish as sometimes thought.
肾上腺嗜铬细胞是神经内分泌系统的重要组成部分，在应激条件下会将儿茶酚胺释放到血液中，从而调节许多生理过程。除了儿茶酚胺外，嗜铬细胞还能合成一系列肽类，包括神经肽Y。尽管儿茶酚胺和肽类都包含在致密核心颗粒中，但它们是否共包装尚不清楚。在此，我研究单个致密核心颗粒是否能同时装载这两种类型的递质分子。利用电流测定法和FMRF酰胺标记，我在体外同时测量了小鼠嗜铬细胞中儿茶酚胺和一种神经肽的分泌。我发现单个致密核心颗粒的融合会将两种类型的递质释放到细胞外空间。大量的肽在1-2毫秒内从融合的颗粒中逸出：几乎与儿茶酚胺一样快。这表明肽分泌的动力学可能并不像有时认为的那样缓慢。
