Malpighian Tubule Transport Physiology: Mechanisms and Regulation

9604394 Beyenbach昆虫肾脏的功能是显著的，因为尿液完全由分泌机制产生，而不是像人类肾脏那样通过过滤产生。分泌受激素调节，使得昆虫既不水分不足也不水分过多。最近发现的一种激素，Culex-利尿肽，保护昆虫免受过度水合，对吸血昆虫特别重要。蚊子吃了一顿血餐后，所携带的有效载荷是它体重的两倍多，如果不是因为它对血餐的处理速度极快，蚊子会威胁飞行，造成灾难性的后果。令人惊讶的是，当进食仍在进行时，大量摄入的血液被消化、吸收并从肾脏排出，从一端对宿主排尿，而从另一端吸血，这是雪上加霜。这样做，蚊子摆脱了不需要的盐，水和血餐的重量，然后飞走，留下糖，脂肪和蛋白质供自己使用。肾脏中盐和水的高速率运输显然是由激素Culex-利尿肽引发的，该激素刺激通过肾脏细胞的运输，并且令人惊讶的是，也是肾脏细胞之间的运输！肾脏细胞之间的运输及其激素的调节是生物学中的一个新现象，对于我们理解从肾脏到肠、胃、胰腺和分泌腺的所有上皮细胞中的transpsort功能具有潜在的重要意义。理解上皮细胞间转运的机制和调节的潜在生物医学和临床应用是不可否认的。

9604394 Beyenbach The function of insect kidneys is remarkable in that urine is produced entirely by secretory mechanisms and not by filtration as in human kidneys. Secretion is regulated by hormones such that the insect is neither under- nor over-hydrated. One recently discovered hormone, Culex-diuretic peptide, protects the insect against over-hydration, particularly important for blood-feeding insects. Taking a blood-meal, the mosquito takes on a payload more than twice its own body weight threatening flight with disastrous consequences were it not for extremely fast processing of the meal. Astonishingly, much of the ingested blood is digested, absorbed and excreted from the kidney while the meal is still in progress with the effect of urinating on the host from mne end while sucking blood from the other end, adding insult to injury. Doing so, the mosquito gets rid of the unwanted salt, water and weight of the blood meal and then flies away keeping sugars, fats, and proteins for its own use. High rates of salt and water transport in the kidney apparently are triggered by the hormone Culex-diuretic peptide which stimulates transport through the cells of the kidney and, surprisingly, also between the cells of the kidney! Transport between the cells of kidney and its regulation by a hormone is a new phenomenon in biology with potentially important lessons for our understanding of tranpsort functions in all epithelia, from kidney to intestine, stomach, pancreas, and secretory glands. Potential biomedical and clinical applications of understanding the mechanism and regulation of epithelial transport between cells cannot be denied.