Vasodilator effects of C-type natriuretic peptide on cerebral arterioles in rats

The vasodilator effects of C-type natriuretic peptide (CNP) were investigated in isolated rat cerebral arterioles. CNP caused dose-dependent vasodilation, maximally by 10.0±2.2% at 10⁻⁶ M. The median effective concentration (EC₅₀) was 5.2×10⁻¹⁰ M. In contrast, atrial natriuretic peptide and B-type natriuretic peptide, other members of the natriuretic peptide family, produced little or no vasodilation. Pretreatment with methylene blue (10⁻⁴ M) abolished CNP-induced vasodilation, whereas pretreatment with N^G-monomethyl-

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-arginine or indomethacin did not inhibit vasodilation. Thus, CNP is suggested to cause significant vasodilation in cerebral arterioles via a cyclic guanosine monophosphate-dependent mechanism. © 1997 Elsevier Science B.V. All rights reserved.     

心脏病患者血浆心钠素浓度初探

本文报道了采用放射免疫分析法检测的136例健康人和95例心脏病患者血浆心钠素含量的结果。健康人血浆心钠素含量为460．86±23．68ng／L，男女之间，年龄之间无明显差异。心脏病患者的血浆心钠素浓度均高于健康人，心脏病患者心功能越差，血浆心钠素浓度越高，其中以肺心病组变化最为明显。     

Renal interstitial pressure and tubuloglomerular feedback control in rats during infusion of atrial natriuretic peptide (ANP)

Atrial natriuretic peptide (ANP), injected at physiological concentrations, is known to induce both natriuresis and diuresis. It has been suggested by some investigators that these changes result from an increasing glomerular filtration rate (GFR), but others have been unable to demonstrate an increased GFR. The tubuloglomerular feedback (TGF) mechanism is an important regulator of GFR, and the sensitivity of TGF is decreased during ANP administration. Furthermore, resetting of TGF is, in most instances, related to changes in renal interstitial hydrostatic and oncotic pressures. It is also known that ANP may increase capillary permeability which may change renal interstitial pressure. The present study was performed to examine renal interstitial pressures and the TGF mechanism during ANP infusion. In accordance with previous studies, TGF sensitivity was found to be decreased. The tubular flow rate which elicited half the maximal drop in stop-flow pressure (P_sf) was increased from 18.5 to 25.7 nl min^-1. In contrast, ANP infusion resulted in a decreased interstitial hydrostatic pressure and an increased interstitial oncotic pressure. From previous experiments, such changes in interstitial pressures would be expected to increase TGF sensitivity. The changes in interstitial pressure cannot, therefore, directly explain the resetting of the feedback mechanism. In conclusion, the present paper shows a decreased renal net interstial pressure after intravenous administration of ANP.     

劳动复合方案对小鼠血浆心钠素和耐力的实验研究

昆明种小鼠56只，在两个海拔高度上（300m和5000m）各分为两个组（对照组和复合组），分别给予相应的处理因素后，检测其血浆ANP水平和游泳时间。结果表明，小鼠在海拔5000m生活48h后，其血浆ANP较海拔300m小鼠降低52．87％，而其游泳时间则增长91．59％；在两个海拔高度上，复合组血浆ANP都较对照组降低，而游泳时间都长于对照组．提示复合方案提高高原劳动能力的机理，可能与降低体内血浆ANP水平有关。     

心钠素免疫反应在豚鼠耳蜗中的整体分布

目的 :研究豚鼠耳蜗中心钠素 (ANP)免疫反应的分布状态 ,为探讨ANP在耳蜗中的作用提供形态学基础。方法 :采用免疫组织化学ABC法检测ANP在正常豚鼠耳蜗各组织中的分布特征。结果 :在耳蜗 1～ 4回的血管纹、螺旋缘、Corti’s器、螺旋神经节和中间阶外壁的螺旋韧带均发现有ANP反应 (ANP IR)阳性产物 ;而耳蜗骨壁、前庭膜、鼓阶外壁的螺旋韧带和鼓阶的下壁ANP IR为阴性。结论 :耳蜗中的ANP在内耳淋巴液的生成和声信号的传导以及耳蜗血流量的调节等方面可能担负着重要的作用     

Atrial amyloid deposits in the failing human heart display both atrial and brain natriuretic peptide-like immunoreactivity

Atrial amyloid deposits are common in the ageing human heart and contain alpha-atrial natriuretic peptide (proANP99-126) immunoreactivity. However, atrial myocytes secrete both amino and carboxy terminal fragments of the ANP prohormone (proANP1-126) and also express an homologous, but separate brain natriuretic peptide (BNP). Characteristic amyloid deposits were identified in the atria of 9/22 patients (26-63 years of age) with end-stage heart failure. Amyloid fibrils displayed immunoreactivity for both amino and carboxy terminal fragments of proANP1-126 and for the distinct BNP sequence. As in other endocrine organs, both mature and precursor peptide sequences appear to be constituents of amyloid fibrils. Whilst immunoreactivity for cardiac peptide hormones is co-localized in atrial amyloid deposits, it is uncertain whether the increase in natriuretic peptide expression which accompanies cardiac failure contributes to the incidence of isolated atrial amyloidosis.     

Effects of calcium supplementation and deoxycorticosterone on plasma atrial natriuretic peptide and electrolyte excretion in spontaneously hypertensive rats

The effects of calcium and the mineralocorticoid deoxycorticosterone (DOC) on blood pressure were studied in four groups of spontaneously hypertensive rats (SHR): (1) control; (2) calcium; (3) deoxycorticosterone and; (4) deoxycorticosterone + calcium. Calcium was given as 1.5% calcium chloride in drinking fluid and deoxycorticosterone by weekly subcutaneous injections (25 mg kg^-1). During the nine weeks of treatment the increase in systolic blood pressure was enhanced in the deoxycorticosterone and attenuated in the calcium group, whereas the deoxycorticosterone + calcium group did not deviate from control. Total plasma calcium was elevated in the calcium group. Plasma concentrations of sodium and atrial natriuretic peptide (ANP) were increased by deoxycorticosterone while neither of the calcium-treated groups differed from control in these respects. Urinary excretions of calcium and sodium were increased in both groups receiving calcium, and also the deoxycorticosterone group excreted more calcium into urine than the control. Adrenergic nerve density in a section of the mesenteric artery and the urinary excretion of noradrenaline and adrenaline were similar in all study groups. The results indicate that calcium supplementation can attenuate the development of hypertension and prevent the deoxycorticosterone-induced blood pressure rise in SHR, possibly by influencing sodium metabolism as seen in increased natriuresis, and by preventing the actions of deoxycorticosterone on sodium balance.     

心钠素对培养人心包间皮细胞内钙离子浓度的影响

目的　探讨心纳素与人类心包间皮细胞之间的关系。　方法　分离人心包间皮细胞进行体外培养 ,用Fluo 3作为钙的指示剂 ,利用激光共聚焦显微镜测定 10 - 9mol L ,10 - 1 0 mol L ,10 - 1 1 mol L心钠素 (ANP)分别用作用于人心包间皮细胞后细胞内Ca2 (Ca2 )浓度变化。　结果　人心包间皮细胞存在细胞内Ca2 浓度的改变 ,随着ANP浓度的增加 ,细胞内Ca2 浓度出现非常明显的变化 (P <0 0 0 0 1) ;细胞内Ca2 浓度随时间变化也出现明显的变化 (P <0 0 0 0 1) ;不同时间测定的钙离子浓度与ANP浓度之间存在着交互作用 (P <0 0 0 0 1)。　结论　人心包间皮细胞存在细胞内Ca2 的改变 ;不同浓度的ANP作用于间皮细胞后引起细胞内Ca2 浓度出现明显不同的改变     

肾脏微血管内的压力分布与ANP的作用

本实验在40只大鼠经伺服零测压技术测定的肾脏微血管内压力分布及其ANP的作用均随血管树各段的口径变化而改变。分析小球前各段血管的压力降所占动脉总压降的比例得知:小叶间动脉占总压降的88％。肾小球毛细血管和出球小动脉亦具有较大的压力降。正常对照情况下,肾小球前血管内的压力分布与内径呈直线相关(r=0.869,n=65,P<0.01),其回归方程为平均压()=34.71±0.798×血管内径(D)。给ANP后肾小球前血管内的压力与内径仍呈直线相关(r=0.931,P<0.01),回归方程式为()=38.53+0.765D,其曲线右上移。本文结果提示,肾小球前微血管内压力分布与血管内径密切相关。小叶间动脉的阻力较大。     

房间隔缺损患者行经封堵术后右心室容量及血浆心钠素的变化

目的:观察房间隔缺损(ASD)封堵术后右心室容量及血浆心钠素(ANP)的变化。方法:对23例成功行经导管ASD封堵术的患者,分别于封堵术前、术后3天取静脉血,采用放射免疫法测定血浆ANP浓度;并于术前、术后3天行心脏三维超声心动图检查,测量右心室腔容量;并对ANP与肺动脉压(PAP)、右心室腔容量、右室射血分数进行相关分析。结果:ASD封堵术后3天血浆ANP浓度较术前明显降低(101.89±35.80ng/Lvs153.46±74.55ng/L,P<0.01);封堵术后3天右心室容量较术前明显缩小,差异有统计学意义(P<0.05),相关分析显示:ASD患者血浆ANP浓度与PAP(r=0.74)、右心室舒张末期容量(r=0.50)、收缩末期容量(r=0.50)分别呈正相关(P均<0.05)、与右室射血分数呈负相关(r=-0.38,P<0.05)。结论:ASD封堵术后血浆心钠素浓度明显降低,右心室腔明显缩小。