Chowdhury P S, Guo X, Wakade T D, Przywara D A, Wakade A R
Department of Pharmacology, Wayne State University, School of Medicine, Detroit, MI 48201.
Neuroscience. 1994 Mar;59(1):1-5. doi: 10.1016/0306-4522(94)90092-2.
Secretion of catecholamines from chromaffin cells is mediated by cholinergic and peptidergic neurotransmitters. The cholinergic transmitter acetylcholine activates both nicotinic and muscarinic receptors to trigger catecholamine secretion in rat adrenal medulla. Vasoactive intestinal polypeptide (VIP) has been identified as the peptidergic transmitter in rat adrenal medulla and may also be the non-cholinergic transmitter in bovine adrenal. Pituitary adenylate cyclase activating polypeptide (PACAP), a VIP-like secretin peptide, is also found in the adrenal, and is a potent secretagogue. Thus, PACAP may be another peptidergic transmitter at the adrenal synapse. A most intriguing property of rat chromaffin cells is that stimulation of nicotinic, muscarinic, VIP or PACAP receptors are each able to produce robust catecholamine secretion on their own. This raises the question of whether a single chromaffin cell can respond to each of the above agonists or whether the secretion is due to subpopulations of chromaffin cells. This issue was addressed by using electrochemical techniques to monitor exocytosis from individual chromaffin cells in culture. We demonstrate that acetylcholine, nicotine, muscarine, VIP and PACAP are each able to evoke catecholamine secretion from a single chromaffin cell. Some cells only responded to acetylcholine. Furthermore, each agonist produced a distinct pattern of exocytosis. Muscarine-evoked secretion exhibited a latency of 0.5-2 s, but exocytosis persisted up to 30 s following 500 ms stimulation. Nicotine produced an immediate response which usually ended within 10 s. The secretory pattern following acetylcholine appeared to be the sum of the nicotinic and muscarinic patterns, showing both rapid onset and longer duration.(ABSTRACT TRUNCATED AT 250 WORDS)
嗜铬细胞分泌儿茶酚胺是由胆碱能和肽能神经递质介导的。胆碱能递质乙酰胆碱激活烟碱型和毒蕈碱型受体，从而触发大鼠肾上腺髓质中的儿茶酚胺分泌。血管活性肠肽（VIP）已被确定为大鼠肾上腺髓质中的肽能递质，也可能是牛肾上腺中的非胆碱能递质。垂体腺苷酸环化酶激活多肽（PACAP）是一种类似VIP的促胰液素肽，也存在于肾上腺中，是一种有效的促分泌素。因此，PACAP可能是肾上腺突触处的另一种肽能递质。大鼠嗜铬细胞一个非常有趣的特性是，刺激烟碱型、毒蕈碱型、VIP或PACAP受体各自都能独立产生强烈的儿茶酚胺分泌。这就提出了一个问题，即单个嗜铬细胞是否能对上述每种激动剂作出反应，或者分泌是否是由于嗜铬细胞亚群所致。通过使用电化学技术监测培养中单个嗜铬细胞的胞吐作用来解决这个问题。我们证明，乙酰胆碱、尼古丁、毒蕈碱、VIP和PACAP各自都能从单个嗜铬细胞中诱发儿茶酚胺分泌。一些细胞只对乙酰胆碱有反应。此外，每种激动剂都产生了独特的胞吐模式。毒蕈碱诱发的分泌潜伏期为0.5 - 2秒，但在500毫秒刺激后胞吐作用持续长达30秒。尼古丁产生即时反应，通常在10秒内结束。乙酰胆碱后的分泌模式似乎是烟碱型和毒蕈碱型模式的总和，显示出快速起效和持续时间更长的特点。（摘要截短至250字）
