Evidence for a preglomerular oxygen diffusion shunt in rat renal cortex

Schurek, H. J.; Jost, Uwe; Baumgärtl, H.; Bertram, Harald; Heckmann, U

doi:10.1152/ajprenal.1990.259.6.f910

Cited by 113 publications

(145 citation statements)

References 0 publications

Supporting

Mentioning

133

Contrasting

Unclassified

Order By: Relevance

“…In terms of understanding the role of the HIF-1 system in physiology and disease, an important question is the relationship between local pO 2 and HIF activation. In cell culture under standard conditions, HIF-1 is usually barely detectable by electrophoretic mobility shift assay or by immunoblotting for HIF-␣ subunits.…”

Section: At What Level Of Oxygenation Is Hif-1 Activated and How Doementioning

confidence: 99%

“…Less well recognized is that diffusion of oxygen directly from arterial to venous vessels seems to remove approximately 50% of the oxygen contained in arterial blood before it arrives at the glomerulus. This probably occurs mainly at the level of the interlobular vessels (2).…”

Section: Oxygenation In the Kidneymentioning

confidence: 99%

“…Intriguing is that compromised EPO production is a striking feature of many kidney diseases; understanding why this is so could provide insight into the events that lead to continuing renal damage and clues as to how it could be prevented. Second, parts of the kidney experience low oxygen tensions even under normal circumstances (2), and the kidney is very sensitive to hypoperfusion injury (3). Third, constitutive activation of HIF-1 occurs in the great majority of clear cell renal cell carcinomas (CCRCC), which is the most common form of cancer affecting the kidney (4).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Hif-1

Maxwell

2003

Journal of the American Society of Nephrology

117

View full text Add to dashboard Cite

Section: At What Level Of Oxygenation Is Hif-1 Activated and How Doementioning

confidence: 99%

Section: Oxygenation In the Kidneymentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Hif-1

Maxwell

2003

Journal of the American Society of Nephrology

117

View full text Add to dashboard Cite

“…However, direct measurements of PO2 in the renal cortex yielded surprisingly low values [28]. Even the POz of the glomerular effluent, which was measured at the renal surface, was far below the value in the renal vein [28]. These results suggest an arterio-venous oxygen shunt.…”

Section: Structural Changes In the Kidney In Response To Anemiamentioning

confidence: 89%

“…The blood supply to this organ is very high, and the fractional extraction of oxygen amounts to only about 8%. However, direct measurements of PO2 in the renal cortex yielded surprisingly low values [28]. Even the POz of the glomerular effluent, which was measured at the renal surface, was far below the value in the renal vein [28].…”

Section: Structural Changes In the Kidney In Response To Anemiamentioning

confidence: 95%

Structure-function correlations in erythropoietin formation and oxygen sensing in the kidney

et al. 1991

View full text Add to dashboard Cite

Summary. The kidney is the main site of erythropoietin (EPO) formation. Oxygen sensing in the kidney itself plays a major role in the control of EPO synthesis. By in situ hybridization it has been established that the EPO-producing cells are situated in the interstitium of the cortical labyrinth, but they have not been precisely identified. Morphological findings provide new insights into the location and mechanism of oxygen sensing in the kidney. In addition to causing an increase in the number of cells containing EPO messenger RNA, anemia provokes structural changes exclusively in the cortical labyrinth. Specifically, the fibroblasts become enlarged and show increased activity of 5'-nucleotidase, and the $1 segment of the proximal tubule shows similar alterations as in various models of hypoxia. Thus, structures that are situated in the close vicinity of the EPO-producing cells appear to be sensitive to decreased oxygen delivery.Key words: Erythropoietin -Kidney -AnemiaOxygen -Proximal tubule -Endothelium -Fibroblasts consisting of a polypeptide chain of 165 aminoacids and one O-linked and three N-linked carbohydrate chains [23,24]. It induces proliferation and differentiation of late erythroid precursors and thereby determines the rate of red cell formation [7]. EPO plasma concentrations are determined mainly by the rate of EPO production in the kidneys, which in turn is negatively controlled by oxygen delivery to the kidneys. Renal EPO formation is therefore an essential part of a negative feedback loop guaranteeing normal tissue oxygenation (Fig. 1). Thus, renal EPO production, and in consequence plasma EPO levels, are elevated during anemia (Fig. 2), arterial hypoxia, and increased oxygen affinity of hemoglobin, and they are reduced during polycythemia [3]. Circumstantial evidence, moreover, suggests that it is the renal interstitial oxygen pressure (PO2) that governs EPO production in the kidney. The mechanism by which renal EPO formation is adapted to oxygen delivery and local PO 2 is only poorly understood. In the following we will consider structural and functional relationships within the kidney that could be of importance for the oxygen-dependent regulation of EPO production.The kidney, aside from its roles in waste excretion and water and electrolyte homeostasis, carries responsibility for tissue oxygenation since it is, at least in adult life, the main site of erythropoietin (EPO) formation. EPO is a glycoprotein hormone * Preprint of a lecture to be read at the 22nd Congress of the "Gesellschaft ffir Nephrologie", Heidelberg, September 15-18, 1991 (Editor: Prof. Dr. E. Ritz, Heidelberg) Abbreviations: EPO=erythropoietin; MHC II=major histocompatibility class II antigen; PAS=Period-acid-Schiff reaction; Sl=first segment of proximal tubule; S2=second segment of proximal tubule Structural Aspects of EPO Formation TopographyAttempts to identify the site of erythropoietin formation in the kidney have been made using both immunohistochemistry and in situ hybridization. The first method failed to reve...

show abstract

Dual Effect of Adenosine A₁ Receptor Activation on Renal O₂ Consumption

Babich

Vadnagara

Sole

2015

Journal Cellular Physiology

View full text Add to dashboard Cite

The high requirement of O2 in the renal proximal tubule stems from a high rate of Na(+) transport. Adenosine A1 receptor (A1R) activation regulates Na(+) transport in this nephron segment. Thus, the effect of the acute activation and the mechanisms of A1R on the rate of O2 consumption were evaluated. The A1R-antagonist, 8-cyclopentyl-1,3-dipropylxanthine (CPX) and adenosine deaminase (ADA), which metabolize endogenous adenosine, reduced O2 consumption (40-50%). Replacing Na(+) in the buffer reversed the ADA- or CPX-mediated reduction of O2 consumption. Blocking the Na/H-exchanger activity, which decreases O2 usage per se, did not enhance the ADA- or CPX-induced inhibition of O2 consumption. These data indicate that endogenous adenosine increases O2 usage via the activation of Na(+) transport. In the presence of endogenous adenosine, A1R was further activated by the A1R-agonist N(6)-cyclopentyladenosine (CPA); CPA inhibited O2 usage (30%) and this effect also depended on Na(+) transport. Moreover, a low concentration of CPA activated O2 usage in tissue pretreated with ADA, whereas a high concentration of CPA inhibited O2 usage; both effects depended on Na(+). Protein kinase C signaling mediated the inhibitory effect of A1R, while adenylyl cyclase mediated its stimulatory effect on O2 consumption. In summary, increasing the local concentrations of adenosine can either activate or inhibit O2 consumption via A1R, and this mechanism depends on Na(+) transport. The inhibition of O2 usage by A1R activation might restore the compromised balance between energy supply and demand under pathophysiological conditions, such as renal ischemia, which results in high adenosine production.

show abstract

Evidence for a preglomerular oxygen diffusion shunt in rat renal cortex

Cited by 113 publications

References 0 publications

Hif-1

Hif-1

Structure-function correlations in erythropoietin formation and oxygen sensing in the kidney

Dual Effect of Adenosine A₁ Receptor Activation on Renal O₂ Consumption

Contact Info

Product

Resources

About

Evidence for a preglomerular oxygen diffusion shunt in rat renal cortex

Cited by 113 publications

References 0 publications

Hif-1

Hif-1

Structure-function correlations in erythropoietin formation and oxygen sensing in the kidney

Dual Effect of Adenosine A1 Receptor Activation on Renal O2 Consumption

Contact Info

Product

Resources

About

Dual Effect of Adenosine A₁ Receptor Activation on Renal O₂ Consumption