Schlondorff D
Am J Med. 1986 Aug 25;81(2B):1-11. doi: 10.1016/0002-9343(86)90903-4.
Prostaglandins are substances that exert their effects at the site of their production. Therefore, the synthesis and effects of prostaglandins have to be considered separately for each nephron segment. In the cortex, major sites of prostaglandin synthesis include arteries and arterioles as well as the glomerulus. At these sites, prostaglandins are important in maintaining blood flow and glomerular filtration, especially during conditions of enhanced vasoconstrictor activity. Vasoconstrictors such as angiotensin II, norepinephrine, and vasopressin increase production of the vasodilator prostaglandins, thereby preventing an overshoot of their action. The role of arteriolar-glomerular prostaglandins in maintaining blood flow and filtration may be even more prominent during renal diseases. The proximal tubule and the loop of Henle show little ability to produce prostaglandins, but may generate considerable amounts of epoxygenase products of arachidonic acid. These epoxygenase products may play a prostaglandin-independent role in water and electrolyte transport in the thick ascending loop of Henle and the collecting tubule. Both the cortical and the medullary collecting tubules produce large amounts of prostaglandins, predominantly prostaglandin E2 (PGE2). In these segments, synthesis of PGE2 is stimulated by bradykinin and to a somewhat more variable degree by vasopressin. The PGE2 generated antagonizes the hydroosomotic effect of vasopressin both in vivo and in vitro, and may influence electrolyte excretion. Thus, the overall role of PGE2--and possibly of epoxygenase products of arachidonic acid--in tubular functions seems to be one of local modulation of water and electrolyte transport. Finally, interstitial cells are a major site of medullary prostaglandin production. Prostaglandins generated by the interstitial cells may play a role in maintaining blood flow to this poorly oxygenated and hypertonic region of the kidney.
前列腺素是在其产生部位发挥作用的物质。因此，必须针对每个肾单位节段分别考虑前列腺素的合成和作用。在皮质中，前列腺素合成的主要部位包括动脉、小动脉以及肾小球。在这些部位，前列腺素对于维持血流和肾小球滤过非常重要，尤其是在血管收缩活性增强的情况下。血管收缩剂如血管紧张素II、去甲肾上腺素和血管加压素会增加血管舒张性前列腺素的产生，从而防止其作用过度。在肾脏疾病期间，小动脉 - 肾小球前列腺素在维持血流和滤过方面的作用可能更为突出。近端小管和髓袢产生前列腺素的能力较弱，但可能产生大量花生四烯酸的环氧合酶产物。这些环氧合酶产物可能在髓袢升支粗段和集合小管的水和电解质转运中发挥独立于前列腺素的作用。皮质和髓质集合小管都产生大量前列腺素，主要是前列腺素E2（PGE2）。在这些节段中，缓激肽可刺激PGE2的合成，血管加压素在一定程度上也可刺激其合成，但其程度变化较大。所产生的PGE2在体内和体外均拮抗血管加压素的水渗透作用，并可能影响电解质排泄。因此，PGE2以及可能的花生四烯酸环氧合酶产物在肾小管功能中的总体作用似乎是对水和电解质转运进行局部调节。最后，间质细胞是髓质前列腺素产生的主要部位。间质细胞产生的前列腺素可能在维持肾脏这个低氧和高渗区域的血流方面发挥作用。
