Fraenkel M B, Potocnik S J, Wintour E M
Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Victoria, Australia.
Am J Physiol. 1994 Nov;267(5 Pt 2):F825-30. doi: 10.1152/ajprenal.1994.267.5.F825.
This study examined the ontogeny of the mRNA for three atrial natriuretic peptide (ANP) receptors in the ovine fetal kidney and the effect of systemic ANP infusion in the very immature ovine fetus. mRNA was isolated from the kidneys of 60-, 100-, and 140-day fetuses (n = 4 at each age). Northern blots [5 micrograms poly(A)+ RNA per track] were probed for the guanylate cyclase (GC)-A, GC-B, and clearance receptors, using beta-actin as a control for variations in loading. The results were quantitated using laser densitometry. Levels of clearance receptor mRNA were significantly higher in 140-day than 60-day fetal kidneys (P < 0.05), whereas levels of mRNA for the GC-A and GC-B receptors remained steady. We propose that binding of ANP to an increased number of C receptors in the late-gestation fetal kidney could explain the previously documented increase in total ANP receptor number in late-gestation ovine kidneys without increased ANP biological activity. Systemic ANP infusion into four fetuses of approximately 74 days gestation resulted in a natriuresis and diuresis, indicating the presence of functional ANP receptors in the ovine kidney early in gestation.
本研究检测了绵羊胎儿肾脏中三种心房利钠肽（ANP）受体的mRNA的个体发生情况，以及向极不成熟的绵羊胎儿体内全身输注ANP的效果。从60日龄、100日龄和140日龄胎儿的肾脏中分离mRNA（每个年龄段n = 4）。使用β-肌动蛋白作为上样量变化的对照，对Northern印迹（每条泳道5微克聚腺苷酸加尾RNA）进行鸟苷酸环化酶（GC）-A、GC-B和清除受体检测。结果采用激光密度测定法定量。140日龄胎儿肾脏中清除受体mRNA水平显著高于60日龄胎儿肾脏（P < 0.05），而GC-A和GC-B受体的mRNA水平保持稳定。我们认为，在妊娠晚期胎儿肾脏中，ANP与数量增加的C受体结合，可以解释先前记录的妊娠晚期绵羊肾脏中总ANP受体数量增加而ANP生物活性未增加的现象。向大约74日龄妊娠的四只胎儿体内全身输注ANP导致了利钠和利尿，表明在妊娠早期绵羊肾脏中存在功能性ANP受体。
