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Edlund, Jenny
Publications (3 of 3) Show all publications
Edlund, J., Fasching, A., Liss, P., Hansell, P. & Palm, F. (2010). The roles of NADPH-oxidase and nNOS for the increased oxidative stress and the oxygen consumption in the diabetic kidney. Diabetes/Metabolism Research Reviews, 26(5), 349-356
Open this publication in new window or tab >>The roles of NADPH-oxidase and nNOS for the increased oxidative stress and the oxygen consumption in the diabetic kidney
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2010 (English)In: Diabetes/Metabolism Research Reviews, ISSN 1520-7552, E-ISSN 1520-7560, Vol. 26, no 5, p. 349-356Article in journal (Refereed) Published
Abstract [en]

Background

Sustained hyperglycaemia induces increased renal oxygen consumption resulting in reduced oxygen availability in the diabetic kidney. We investigated the roles of the nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase and the neuronal nitric oxide synthase (nNOS) for the increased oxygen consumption in streptozotocin-diabetic rats.

Methods

Oxygen consumption was measured in isolated proximal tubular cells (PTC) from streptozotocin-induced diabetic rats (n = 7-9 per group) with and without chronic treatment with apocynin, a NADPH-oxidase inhibitor, or S-methyl-L-thiocitrulline (SMTC), a selective nNOS inhibitor, or a combination of the two and the results were compared to normoglycaemic controls (n = 10). Oxidative stress was estimated from thiobarbituric acid reactive substances and protein expression measured by Western blot.

Results

Proximal tubular cells from untreated diabetic rats had increased oxygen consumption compared to controls (40.6 +/- 7.9 versus 10.9 +/- 2.0 nmol/mg protein/min). All treatments reduced the diabetes-induced increase in oxygen consumption (apocynin 10.5 +/- 1.7, SMTC 19.7 +/- 3.0 and apocynin +/- SMTC 21.6 +/- 3.6 nmol/mg protein/min). Neither apocynin nor SMTC had any effect on the oxygen consumption in cells pre-incubated with ouabain, an inhibitor of active electrolyte transport. Oxidative stress was elevated in the diabetic kidney and inhibited by all treatments. The increased oxygen consumption by diabetic proximal tubular cells correlated with increased protein expressions of p47phox and nNOS and the treatments prevented these increases.

Conclusions

Diabetes induces oxidative stress, which increases oxygen consumption in proximal tubular cells. Inhibition of either NADPH-oxidase or nNOS prevented the increased oxygen consumption. The effect of blocking both these enzymes was less than additive suggesting overlapping pathways which warrant further studies.

Keywords
NADPH-oxidase, neuronal nitric oxide synthase, diabetes mellitus, oxygen consumption, oxidative stress
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-99322 (URN)10.1002/dmrr.1099 (DOI)000280033900004 ()20583310 (PubMedID)
Available from: 2010-12-09 Created: 2013-10-15 Last updated: 2017-12-06
Edlund, J., Hansell, P., Fasching, A., Liss, P., Weis, J., Glickson, J. D. & Palm, F. (2009). Reduced oxygenation in diabetic rat kidneys measured by T2* weighted magnetic resonance micro-imaging. Advances in Experimental Medicine and Biology, 645, 199-204
Open this publication in new window or tab >>Reduced oxygenation in diabetic rat kidneys measured by T2* weighted magnetic resonance micro-imaging
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2009 (English)In: Advances in Experimental Medicine and Biology, ISSN 0065-2598, E-ISSN 2214-8019, Vol. 645, p. 199-204Article in journal (Refereed) Published
Abstract [en]

By applying invasive techniques for direct measurements of oxygen tension, we have reported decreased kidney oxygenation in experimental diabetes in rats. However, the non-invasive MRI technique utilizing the BOLD effect provides several advantages with the possibility to perform repetitive measurements in the same animals and in human subjects. In this study, we applied a modified single gradient echo micro-imaging sequence to detect the BOLD effect in kidneys of diabetic rats and compared the results to normoglycemic controls. All measurements were performed on inactin-anaesthetized adult male Wistar Furth rats. Diabetes was induced by streptozotocin (45 mg/kg) 14 days prior to MRI-analysis. Sixteen T2*-weighted image records (B0=1.5 T) were performed using radiofrequency spoiled gradient echo sequence with 2.6 ms step increments of TE (TE1=12 ms), while TR (75 ms) and bandwidth per pixel (71.4 Hz) were kept constant. T2* maps were computed by mono-exponential fitting of the pixel intensities. Relaxation rates R2* (1/T2*) in cortex and outer stripe of the outer medulla were similar in both groups (cortex for controls 22.3 +/- 0.4 vs. diabetics 23.1 +/- 1.8 Hz and outer stripe of outer medulla for controls 24.9 +/- 0.4 vs. diabetics 26.4 +/- 1.8 Hz; n=4 in both groups), whereas R2* was increased in the inner stripe of the outer medulla in diabetic rats (diabetics 26.1 +/- 2.4 vs. controls 18.8 +/- 1.4 Hz; n=4, P<0.05). This study demonstrates that experimental diabetes in rats induces decreased oxygenation of the renal outer medulla. Furthermore, the proposed T2*-weighted MR micro-imaging technique is suitable for detection of regional changes in kidney oxygenation in experimental animal models.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-99314 (URN)19227472 (PubMedID)
Available from: 2009-02-24 Created: 2013-10-15 Last updated: 2017-12-06
Carlström, M., Brown, R., Edlund, J., Sällström, J., Larsson, E., Teerlink, T., . . . Persson, A. E. (2008). Role of nitric oxide deficiency in the development of hypertension in hydronephrotic animals. American Journal of Physiology - Renal Physiology, 294(2), 362-370
Open this publication in new window or tab >>Role of nitric oxide deficiency in the development of hypertension in hydronephrotic animals
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2008 (English)In: American Journal of Physiology - Renal Physiology, ISSN 0363-6127, E-ISSN 1522-1466, Vol. 294, no 2, p. 362-370Article in journal (Refereed) Published
Abstract [en]

Hydronephrotic animals develop renal injury and hypertension, which is associated with an abnormal tubuloglomerular feedback (TGF). The TGF sensitivity is coupled to nitric oxide (NO) in the macula densa. The involvement of reduced NO availability in the development of hypertension in hydronephrosis was investigated. Hydronephrosis was induced by ureteral obstruction in young rats. Blood pressure and renal excretion were measured in adulthood, under different sodium conditions, and before and after chronic administration of either N-G- nitro-L-arginine methyl ester (L-NAME) or L-arginine. Blood samples for ADMA, SDMA, and L-arginine analysis were taken and the renal tissue was used for histology and determination of NO synthase (NOS) proteins. TGF characteristics were determined by stop-flow pressure technique before and after administration of 7-nitroindazole (7-NI) or L-arginine. Hydronephrotic animals developed salt-sensitive hypertension, which was associated with pressure natriuresis and diuresis. The blood pressure response to L-NAME was attenuated and L-arginine supplementation decreased blood pressure in hydronephrotic animals, but not in the controls. Under control conditions, reactivity and sensitivity of the TGF response were greater in the hydronephrotic group. 7-NI administration increased TGF reactivity and sensitivity in control animals, whereas, in hydronephrotic animals, neuronal NOS (nNOS) inhibition had no effect. L-Arginine attenuated TGF response more in hydronephrotic kidneys than in controls. The hydronephrotic animals displayed various degrees of histopathological changes. ADMA and SDMA levels were higher and the renal expressions of nNOS and endothelial NOS proteins were lower in animals with hydronephrosis. Reduced NO availability in the diseased kidney in hydronephrosis, and subsequent resetting of the TGF mechanism, plays an important role in the development of hypertension.

Keywords
ADMA, tubuloglomerular feedback, L-arginine, L-NAME, telemetry, blood pressure
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-99298 (URN)10.1152/ajprenal.00410.2007 (DOI)000252744300010 ()
Available from: 2008-03-28 Created: 2013-10-15 Last updated: 2017-12-06
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