Disease relevance of Juxtaglomerular Apparatus

• Marked hyperglycemia in animals and man leads to "glycogen nephrosis," which affects the distal tubule at the level of the macula densa of the juxtaglomerular apparatus (JGA) [1].
• This study aimed to characterize the influence of acute renal artery stenosis on cyclooxygenase-2 (COX-2) and renin expression in the juxtaglomerular apparatus [2].
• We examined expression of these TGF-beta isoforms in a 50-year-old man with a Bartter's-like syndrome whose renal biopsy specimen showed hyperplasia of the juxtaglomerular apparatus (GA), mild mesangial hypercellularity, focal tubular atrophy, and interstitial fibrosis [3].
• In genetic hypertension, tubuloglomerular feedback responses are enhanced, in part at least because of diminished buffering by macula densa NO and enhanced O2- generation in the juxtaglomerular apparatus [4].
• Kidney biopsies from 15 insulin-dependent diabetes mellitus (IDDM) patients with microalbuminuria were investigated to obtain quantitative data on the juxtaglomerular apparatus [5].

High impact information on Juxtaglomerular Apparatus

• Expression of transforming growth factor beta 3 in hypertrophic juxtaglomerular apparatus [6].
• An in vitro method has been used to examine whether secretion of renin from the juxtaglomerular apparatus is affected by changes in the sodium chloride concentration of the tubular fluid at the macula densa [7].
• Macula densa (MD) cells express COX-2 and COX-2-derived PGs appear to signal the release of renin from the renal juxtaglomerular apparatus, especially during volume depletion [8].
• Tubular transport measurements confirmed that BNZ affected TGF within the juxtaglomerular apparatus [9].
• Injection of anti-Thy 1 antibody that binds the Thy 1 antigen on rat mesangial cells eliminated (> 95%) the mesangial population at 20-28 h, while Thy 1-positive cells in the juxtaglomerular apparatus (JGA) were sequestered from the circulation and survived [10].

Chemical compound and disease context of Juxtaglomerular Apparatus

• Bartter's syndrome without hyperplasia of the juxtaglomerular apparatus, treated with indomethacin [11].
• Prolonged treatment with cyclosporine (CS) results in an irreversible renal lesion consisting of interstitial fibrosis and tubular atrophy, as well as prominent hyperplasia of the juxtaglomerular apparatus (JGA) [12].

Biological context of Juxtaglomerular Apparatus

• Human renin plays an important role in blood pressure homeostasis and is secreted in a regulated manner from the juxtaglomerular apparatus of the kidney in response to various physiological stimuli [13].
• Using hybridization histochemistry, a technique which localizes specific mRNA populations in tissue sections with a 700 base pair recombinant DNA probe which codes for ovine renin, we have localized renin gene expression in the afferent arteriole of the juxtaglomerular apparatus (JGA) in the sheep renal cortex [14].
• AT1-R blockade specifically diminishes oxidative stress and restores NO signaling in the juxtaglomerular apparatus of the SHR [15].
• Upregulation of the inducible cyclooxygenase (COX-2) in the macula densa accompanies the activation of the juxtaglomerular apparatus in many high-renin conditions [16].
• The tubular-vascular connection via the juxtaglomerular apparatus appears to serve two functions, local control of renal vascular resistance and regulation of renin secretion [17].

Anatomical context of Juxtaglomerular Apparatus

• We investigated a possible involvement of the sympathetic nervous system in the parallel increase of renin, cyclooxygenase-2 (COX-2), and neuronal nitric oxide synthase (nNOS) gene expression in the juxtaglomerular apparatus of rat kidneys induced by salt deficiency [18].
• Renin protein levels measured in the kidney medulla, to avoid contribution from juxtaglomerular apparatus cells, were higher in ANG II-infused rats [1.64 +/- 0.3 vs. 1.00 +/- 0.1 densitometric units (DU) compared with sham-operated rats; P < 0.05], and ARB treatment prevented this increase (1.01 +/- 0.1) [19].
• In ADPKD, immunoreactive renin was present in juxtaglomerular apparatus, associated arterioles, and in some cells within the connective tissue surrounding the cysts [20].
• In the normal kidney, renin was confined to the epithelioid cells of the afferent arteriole of the juxtaglomerular apparatus (JGA) [21].
• The juxtaglomerular apparatus in the kidney is important in controlling extracellular fluid volume and renin release [22].

Associations of Juxtaglomerular Apparatus with chemical compounds

• Adenosine has been proposed to act within the juxtaglomerular apparatus (JGA) as a mediator of the inhibition of renin secretion produced by a high NaCl concentration at the macula densa [23].
• The independency of sodium intake and ANG-converting enzyme make the juxtaglomerular apparatus as the site responsible for the production of this ANG unlikely [24].
• The present studies in perfused specimens of the juxtaglomerular apparatus microdissected from rabbit kidneys were performed to quantitatively evaluate the relation between macula densa NaCl concentration and renin secretion and to study the effect of furosemide and verapamil on NaCl dependency of renin release [25].
• Results define the renal cell types involved in prostaglandin autacoid functions within spatially restricted sites such as the juxtaglomerular apparatus, mesangium, distal convolutions and collecting duct, and in compartments of the renal interstitium [26].
• Groups of rats were killed at 6 hr after UN plus DTT, HgCl2 alone, or HgCl2 plus DTT; and determinations of plasma renin activity (PRA) and renin activities of the superficial and deep juxtaglomerular apparatus (JGA) were performed [27].

Gene context of Juxtaglomerular Apparatus

• In the juxtaglomerular apparatus, the inducible isoform of cyclooxygenase, cyclooxygenase-2 (COX-2), is restricted to the macula densa and the cortical thick ascending limb of Henle (cTALH) cells, and is inversely regulated by dietary salt intake [28].
• MCP was predominantly expressed on the juxtaglomerular apparatus [29].
• Juxtaglomerular apparatus was abundant in DAF and MCP but not in HRF20 [30].
• The majority of Ang II receptors in the kidney comprises the AT1 type, whereas AT2 receptors are only expressed by distinct structures such as the renal capsule and the juxtaglomerular apparatus [31].
• The following significant differences exist with respect to other aminopeptidases (aminopeptidase M and gamma-glutamyl transferase), which were also demonstrated: APM shows no dependence on calcium ions; APM and gamma-GT are not demonstrable in the glomerulus or juxtaglomerular apparatus [32].

Analytical, diagnostic and therapeutic context of Juxtaglomerular Apparatus

• We conclude that the expression of renin, COX-2, and nNOS in the juxtaglomerular apparatus during low-salt diet is markedly limited by a direct feedback inhibition through ANG II [33].
• Loop perfusion in control rats with tubular fluid collected in DOCA rats elicited a normal TGF response, showing that TGF inhibition in the DOCA animals is due to changes in the function of the juxtaglomerular apparatus [34].
• Autoradiography shows that axons associated with the juxtaglomerular apparatus are able to incorporate exogenous tritiated norepinephrine [35].
• Functional interpretation of the kidney juxtaglomerular apparatus using renin immunohistochemistry in Bartter's, pseudo-Bartter's and Conn's syndromes [36].
• The response of the juxtaglomerular apparatus to stimuli effecting renin or erythropoietin release in canine renal allografts [37].

References