大鼠肾微血管中心房钠尿肽受体的特性研究

De León H, Gauquelin G, Thibault G, Garcia R

Laboratory of Experimental Hypertension and Vasoactive Peptides, Clinical Research Institute of Montreal, Quebec, Canada.

J Hypertens. 1993 May;11(5):499-508. doi: 10.1097/00004872-199305000-00005.

OBJECTIVE

To characterize [125I]-atrial natriuretic factor [ANF-(99-126)] binding sites in the renal preglomerular microvasculature of Sprague-Dawley rats.

METHODS

Renal preglomerular microvessels were isolated by infusion of a magnetized iron oxide solution into the renal arteries and detachment from non-vascular tissue by a magnetic field. In order to characterize [125I]-ANF-(99-126) binding sites, saturation and competitive binding experiments were performed. To evaluate the proportions of ANF receptor subtypes (ANF-R1, ANF-R2), competition curves were charted in the presence of 10(-6) mol/l C-ANF-(4-23), a specific ligand of ANF-R2 (ANP-C).

RESULTS

[125I]-ANF binding to vascular membranes was saturable and of high affinity. Equilibrium saturation binding curves suggested the presence of one group of high-affinity receptors [equilibrium dissociation constant (Kd) 22 +/- 6 pmol/l; binding capacity (Bmax) 118 +/- 6 fmol/mg protein]. In competitive inhibition experiments, no significant differences were found in binding capacity between experiments performed either in the presence or in the absence of an excess (1 mumol/l) of C-ANF (94 +/- 27 versus 151 +/- 35 fmol/mg protein, respectively), suggesting that most receptors in the renal vasculature are of the subtype ANF-R1. Incubation of renal microvessels with ANF-(99-126) stimulated cyclic GMP production in a dose-related manner. In parallel studies, the proportion of ANF-R1 (ANP-A, -B) and ANF-R2 (ANP-C) receptors in glomeruli, calculated from competitive inhibition experiments, was 86 +/- 2 and 14 +/- 2%, respectively (P < 0.005).

CONCLUSIONS

These results indicate that rat renal preglomerular microvessels contain a high proportion of guanylate cyclase-coupled ANF-R1 (ANP-A, -B) and a low density of ANF-R2 (ANP-C) receptors. This difference in the proportion of ANF receptor subtypes, compared to that reported in glomeruli and other vascular beds, may have physiological significance.

目的

表征[125I] - 心房利钠因子[ANF - (99 - 126)]在Sprague - Dawley大鼠肾小动脉前微血管中的结合位点。

方法

通过将磁化氧化铁溶液注入肾动脉并利用磁场使其与非血管组织分离，从而分离出肾小动脉前微血管。为了表征[125I] - ANF - (99 - 126)结合位点，进行了饱和结合和竞争性结合实验。为了评估ANF受体亚型（ANF - R1、ANF - R2）的比例，在存在10(-6) mol/l C - ANF - (4 - 23)（一种ANF - R2（ANP - C）的特异性配体）的情况下绘制竞争曲线。

结果

[125I] - ANF与血管膜的结合是可饱和的且具有高亲和力。平衡饱和结合曲线表明存在一组高亲和力受体[平衡解离常数（Kd）22±6 pmol/l；结合容量（Bmax）118±6 fmol/mg蛋白质]。在竞争性抑制实验中，在存在或不存在过量（1 μmol/l）C - ANF的实验之间，结合容量未发现显著差异（分别为94±27与151±35 fmol/mg蛋白质），这表明肾血管中的大多数受体是ANF - R1亚型。用ANF - (99 - 126)孵育肾微血管以剂量相关的方式刺激了环磷酸鸟苷（cGMP）的产生。在平行研究中，根据竞争性抑制实验计算得出，肾小球中ANF - R1（ANP - A、-B）和ANF - R2（ANP - C）受体的比例分别为86±2%和14±2%（P < 0.005）。