The bivalence of Juxtaglomerular cells in the maturing rat kidney

Summary A comparative immunofluorescence and light microscopical study of the three cell types of the Juxtaglomerular apparatus (pure muscle cells, pure granular cells and mixed cells) was performed on the growing and maturing kidney of the rat. Mixed cells, containing contractile protein and secretory granules, are detectable on the first postnatal day in about one third of the JGAs. From the third week, the number of bivalent cells increases, while the proportion of pure muscle or pure granular cells decreases. Morphological and functional maturation, achieved by 3 to 4 weeks, is associated with increasing numbers of bivalent cells and a shift in the main site of renin production from the inner to the outer cortical zone.The divergent internal structure of JGA cell types expresses the range of varied differentiation expressed by one cell line. Pure muscle or granular cells are at the extremes of the range and mixed cells take up an intermediate position.     

Dynamics of reactivity of mesenteric microvessels in rats with experimental renal and hormonal hypertension

Reactivity of mesenteric arterioles 10–30 in diameter to application of histamine (100–500 g) adrenalin, and noradrenalin (1–10 g) was studied in rats with experimental renal and hormonal hypertension. The sensitivity of the microvessels to the vasoactive substances was shown to vary with the stage of development of experimental hypertension.Laboratory of General Pathophysiology and Experimental Therapy, Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. M. Chernukh.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 2, pp. 150–152, February, 1976.     

Openers of small conductance calcium-activated potassium channels selectively enhance NO-mediated bradykinin vasodilatation in porcine retinal arterioles

Background and purpose:

Small (SK_Ca or K_Ca2) and intermediate (IK_Ca or K_Ca3.1) conductance calcium-activated potassium channels are involved in regulation of vascular tone and blood pressure. The present study investigated whether NS309 (6,7-dichloro-1H-indole-2,3-dione 3-oxime) and CyPPA (cyclohexyl-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-pyrimidin-4-yl]-amine), which are selective openers of SK_Ca and IK_Ca channels and of SK_Ca2 and SK_Ca3 channels, respectively, enhance endothelium-dependent vasodilatation in porcine retinal arterioles.

Experimental approach:

In porcine retinal arterioles, SK_Ca3 and IK_Ca protein localization was examined by immunolabelling. Endothelial cell calcium was measured by fluorescence imaging. For functional studies, arterioles with internal diameters of 116 ± 2 µm (n = 276) were mounted in microvascular myographs for isometric tension recordings.

Key results:

SK_Ca3 and IK_Ca protein was localized in the endothelium. Bradykinin, but not NS309 or CyPPA increased endothelial cell calcium. Pre-incubation with NS309 or CyPPA enhanced bradykinin relaxation without changing endothelial cell calcium. This enhanced relaxation was abolished by blocking SK_Ca channels with apamin. In the presence of NS309 or CyPPA, mainly inhibition of NO synthase with asymmetric dimethylarginine, but also inhibition of cyclooxygenase with indomethacin, reduced bradykinin relaxation. Bradykinin relaxation was completely abolished by NO synthase and cyclooxygenase inhibition together with a NO scavenger, oxyhaemoglobin.

Conclusions and implications:

In porcine retinal arterioles, bradykinin increases endothelial cell calcium leading to activation of SK_Ca and IK_Ca channels. Without altering endothelial cell calcium, NS309 and CyPPA open SK_Ca channels that enhance NO-mediated bradykinin relaxations. These results imply that opening SK_Ca channels improves endothelium-dependent relaxation and makes this channel a potential target for treatments aimed at restoring retinal blood flow.     

8例高血压急症相关性肾损害的临床病理分析

目的探讨高血压急症相关肾损害的临床、病理特点和预后。方法回顾性分析2003年1月至2014年1月我院明确诊断的8例高血压急症相关性肾损害患者,所有患者均行肾活检病理检查,及相关实验室及影像学检查。结果患者初始平均收缩压/舒张压（232±30/140±13）mm Hg,平均血肌酐值（452±172）μmol/L（190-922）μmol/L。光镜检查显示：所有的肾活检标本均有小动脉洋葱皮样增厚,及肾小球毛细血管袢缺血皱缩,然而未见到小动脉纤维素样坏死。降血压治疗对所有患者有效,并明显改善患者肾功能。结论高血压急症相关肾损害最常见的病理表现是小动脉洋葱皮样增厚和肾小球毛细血管袢缺血性皱缩;严格控制血压可显著改善高血压急症相关肾损害的预后。     

Theophylline dilates rat diaphragm arterioles via the prostaglandins pathway

1. We investigated by intravital microscopy in rats, the in vivo direct effects of theophylline on the diameters of second and third order diaphragm arterioles.
2. Theophylline (1–100 μM) dilated second and third order diaphragm arterioles significantly, and with an amplitude which was not statistically different from the one obtained with adenosine (1–100 μM). Enprofylline (1–100 μM), a theophylline analogue with poor adenosine-receptor antagonism but with similar or higher phosphodiesterases inhibition properties than theophylline, also dilated diaphragm arterioles, causing however, a significantly smaller dilatation than theophylline.
3. Neither the A1 adenosine receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (CPX, 50 nM), nor the A₂ adenosine receptor antagonist 3,7-dimethyl-1-proparglyxanthine (DMPX, 10 μM) reduced significantly theophylline-induced arteriolar dilatation.
4. Theophylline (100 nM) abolished adenosine-induced arteriolar dilatation.
5. The dilatation induced by theophylline was unchanged by the nitric oxide (NO) synthase inhibitor Nω-nitro-L-arginine (NNA, 300 μM).
6. Theophylline-induced arteriolar dilatation was abolished by the prostaglandin synthesis inhibitors mefenamic acid or indomethacin (20 μM).
7. These findings show that theophylline induced a significant dilatation of diaphragm arterioles via the release of prostaglandins.

     

Myogenic tone and neurogenic vasoconstriction in microcirculatory bed of rat cerebral cortex

The reaction of rat parietal cortical vessels to stimulation of the sympathetic ganglion was studied by intravital microscopy. stimulation induced constriction of cerebral arterioles. Clamping of one or both carotid arteries led to myogenic vasodilatation in the majority of cases. Constrictive response of brain arterioles to ganglion stimulation under conditions carotid occlusion did not differ from that under conditions of baseline cerebral blood supply.     

氟伐他汀对自发性高血压大鼠阻力血管结构和功能的影响

目的 探讨氟伐他汀对自发性高血压大鼠（ＳＨＲ）阻力血管结构和功能的影响。方法 ＳＨＲ大鼠出生后８周给予氟伐他汀２０ｍｇ．ｋｇ＾－１．ｄ＾－１。应用计算机图象分析,计算血管壁腔比,观察三组大鼠肠系膜动一级分支及主动脉结构变化,采用离体的主动脉和肠系膜动脉环在管活性药物：去甲肾上腺素和硝普钠反应的敏感性,观察治疗后血管的功能变化。结果 治疗８周后,氟伐他汀组（ＳＨＲｆｌｕ）收缩压比对照组（ＳＨＲ）平均     

Two-photon NADH imaging exposes boundaries of oxygen diffusion in cortical vascular supply regions

Oxygen transport imposes a possible constraint on the brain''s ability to sustain variable metabolic demands, but oxygen diffusion in the cerebral cortex has not yet been observed directly. We show that concurrent two-photon fluorescence imaging of endogenous nicotinamide adenine dinucleotide (NADH) and the cortical microcirculation exposes well-defined boundaries of tissue oxygen diffusion in the mouse cortex. The NADH fluorescence increases rapidly over a narrow, very low pO₂ range with a p₅₀ of 3.4±0.6 mm Hg, thereby establishing a nearly binary reporter of significant, metabolically limiting hypoxia. The transient cortical tissue boundaries of NADH fluorescence exhibit remarkably delineated geometrical patterns, which define the limits of tissue oxygen diffusion from the cortical microcirculation and bear a striking resemblance to the ideal Krogh tissue cylinder. The visualization of microvessels and their regional contribution to oxygen delivery establishes penetrating arterioles as major oxygen sources in addition to the capillary network and confirms the existence of cortical oxygen fields with steep microregional oxygen gradients. Thus, two-photon NADH imaging can be applied to expose vascular supply regions and to localize functionally relevant microregional cortical hypoxia with micrometer spatial resolution.