Friis U G, Jensen B L, Hansen P B, Andreasen D, Skøtt O
IMB, Physiology and Pharmacology, SDU, Odense University Denmark.
Acta Physiol Scand. 2000 Jan;168(1):95-9. doi: 10.1046/j.1365-201x.2000.00645.x.
The cellular events related to secretion of renin are not well understood. Here we review some of the evidence that has led to the current understanding of renin secretion as a process that involves exocytosis as the predominant mode of secretion. This is based on the observation of occasional fusion events between secretory granules and cell membrane and measurement of intermittent secretion of renin from single afferent arterioles, with a renin content of each secretion episode that corresponds to the renin content of one secretory granule. More recently it has been demonstrated that the afferent arterioles lose a large number of renin granules after acute stimulation without changing the average granular volume. Current electrophysiological techniques have now permitted direct measurements of cell membrane capacitance in juxtaglomerular (JG) cells as a measure of net addition (exocytosis) or removal (endocytosis) of membrane material. With this technique we have shown that cAMP, which is a vasodilator and stimulates renin secretion, enhances net exocytosis at low concentrations, while at higher concentrations membrane retrieval processes are also stimulated. We suggest that both exocytosis and endocytosis are regulated processes in the JG-cells and both may be important for the long-term control of renin secretion at the single cell level.
与肾素分泌相关的细胞事件尚未完全明确。在此，我们回顾一些证据，这些证据使我们目前将肾素分泌理解为一个以胞吐作用作为主要分泌方式的过程。这是基于对分泌颗粒与细胞膜之间偶尔发生的融合事件的观察，以及对单个入球小动脉间歇性分泌肾素的测量，每次分泌事件中的肾素含量与一个分泌颗粒中的肾素含量相对应。最近有研究表明，急性刺激后入球小动脉会丢失大量肾素颗粒，但平均颗粒体积不变。目前的电生理技术现已能够直接测量球旁（JG）细胞的细胞膜电容，以此作为膜物质净增加（胞吐作用）或去除（内吞作用）的指标。通过这项技术我们发现，作为血管舒张剂并刺激肾素分泌的环磷酸腺苷（cAMP），在低浓度时增强净胞吐作用，而在高浓度时也会刺激膜回收过程。我们认为，胞吐作用和内吞作用在球旁细胞中都是受调控的过程，并且两者对于单细胞水平上肾素分泌的长期控制可能都很重要。
