Eitle E, Hiranyachattada S, Wang H, Harris P J
Department of Physiology, University of Melbourne, Parkville, Victoria, Australia.
Am J Physiol. 1998 Apr;274(4):C1075-80. doi: 10.1152/ajpcell.1998.274.4.C1075.
Atrial natriuretic factor (ANF) and nitric oxide (NO) stimulate production of guanosine 3',5'-cyclic monophosphate (cGMP) and are natriuretic. Split-drop micropuncture was performed on anesthetized rats to determine the effects of ANF and the NO donor sodium nitroprusside (SNP) on proximal tubular fluid absorption rate (Jva). Compared with control solutions, SNP (10(-4) M) decreased Jva by 23% when administered luminally and by 35% when added to the peritubular perfusate. Stimulation of fluid uptake by luminal angiotensin II (ANG II; 10(-9) M) was abolished by SNP (10(-4) and 10(-6) M). In proximal tubule suspensions, ANF (10(-6) M) increased cGMP concentration to 143%, whereas SNP (10(-6), 10(-5), 10(-4), 10(-3) M) raised cGMP to 231, 594, 687, and 880%, respectively. S-nitroso-N-acetylpenicillamine (SNAP) also raised cGMP concentrations with similar dose-response relations. These studies demonstrate inhibition by luminal and peritubular NO of basal and ANG II-stimulated proximal fluid absorption in vivo. The ability of SNP to inhibit basal fluid uptake whereas ANF only affected ANG II-stimulated transport may be because of production of higher concentrations of cGMP by SNP.
心房利钠因子（ANF）和一氧化氮（NO）可刺激3',5'-环磷酸鸟苷（cGMP）的生成，且具有利钠作用。对麻醉大鼠进行微穿刺，以确定ANF和NO供体硝普钠（SNP）对近端肾小管液吸收率（Jva）的影响。与对照溶液相比，腔内给予SNP（10⁻⁴ M）时，Jva降低23%；加入肾小管周围灌流液时，Jva降低35%。腔内给予血管紧张素II（ANG II；10⁻⁹ M）刺激液体摄取，可被SNP（10⁻⁴和10⁻⁶ M）消除。在近端肾小管悬液中，ANF（10⁻⁶ M）可使cGMP浓度增加至143%，而SNP（10⁻⁶、10⁻⁵、10⁻⁴、10⁻³ M）可分别使cGMP增加至231%、594%、687%和880%。S-亚硝基-N-乙酰青霉胺（SNAP）也可提高cGMP浓度，且具有相似的剂量反应关系。这些研究表明，管腔和肾小管周围的NO可抑制体内基础状态及ANG II刺激的近端肾小管液体吸收。SNP能够抑制基础状态下的液体摄取，而ANF仅影响ANG II刺激的转运，这可能是因为SNP可产生更高浓度的cGMP。
