PP2B-dependent NO production in the medullary thick ascending limb during diabetes

Autor: Jennifer S. Pollock, Jan M. Foster, Pamela K. Carmines
Rok vydání: 2009
Předmět:
Male
Ornithine
Benzylamines
medicine.medical_specialty
Nitric Oxide Synthase Type III
Cell Survival
Physiology
NOS1
Calcineurin Inhibitors
Amidines
Nitric Oxide Synthase Type II
Nitric Oxide Synthase Type I
Nitric Oxide
Diabetes Mellitus
Experimental
Nitric oxide
Cyclic N-Oxides
Rats
Sprague-Dawley
chemistry.chemical_compound
Downregulation and upregulation
Western blot
Internal medicine
medicine
Loop of Henle
Animals
Diabetic Nephropathies
Enzyme Inhibitors
Phosphorylation
Nitrites
Kidney Medulla
medicine.diagnostic_test
biology
Calcineurin
Free Radical Scavengers
Articles
Free radical scavenger
Streptozotocin
Rats
Up-Regulation
Enzyme Activation
Nitric oxide synthase
medicine.anatomical_structure
Endocrinology
chemistry
Cyclosporine
biology.protein
Spin Labels
Nitric Oxide Synthase
medicine.drug
Zdroj: American Journal of Physiology-Renal Physiology. 297:F471-F480
ISSN: 1522-1466
1931-857X
DOI: 10.1152/ajprenal.90760.2008
Popis: Calcineurin (PP2B) has recently been shown to be upregulated in the medullary thick ascending limb (mTAL) during diabetes. The mTAL expresses all three isoforms of nitric oxide synthase (NOS), which are subject to phosphoregulation and represent substrates for PP2B. Therefore, we hypothesized that diabetes induces PP2B-dependent upregulation of NOS activity and NO production in the mTAL. Three weeks after injection of streptozotocin (STZ rats) or vehicle (sham rats), mTAL suspensions were prepared for use in functional and biochemical assays. PP2B activity and expression were increased in mTALs from STZ rats compared with sham. Nitrite production was significantly reduced in mTALs from STZ rats compared with sham. However, incubation with the free radical scavenger, tempol, unmasked a significant increase in nitrite production by mTALs from STZ rats. Inhibition of PP2B attenuated the increase in nitrite production and NOS activity evident in mTALs from STZ rats. Analysis of specific NOS isoform activity revealed increased NOS1 and NOS2 activities in mTALs from STZ rats. All three NOS isoform activities were regulated in a PP2B-dependent manner. Western blot analysis detected no differences in NOS isoform expression, although phosphorylation of pThr495-NOS3 was significantly reduced in mTALs from STZ rats. Phosphorylation of pSer852-NOS1, pSer633-NOS3, and pSer1177-NOS3 was similar in mTALs from STZ and sham rats. Inhibition of PP2B did not alter the phosphorylation of NOS1 or NOS3 at known sites. In conclusion, while NO bioavailability in mTALs is reduced during diabetes, free radical scavenging with tempol unmasks increased NO production that involves PP2B-dependent activation of NOS1 and NOS2.
Databáze: OpenAIRE
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