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The role of nitric oxide in the dysregulation of the urine concentration mechanism in diabetes mellitus.

Cipriani P, Kim SL, Klein JD, Sim JH, von Bergen TN, Blount MA - Front Physiol (2012)

Bottom Line: We examined how lack of NO affects the transporters involved in urine concentration in diabetic animals.UT-A1 and UT-A3 were significantly increased in diabetic rat inner medulla.Our studies found that although diabetic-induced glycosylation remained increased, total protein expression was decreased to control levels in diabetic rats treated with L-NAME.

View Article: PubMed Central - PubMed

Affiliation: Renal Division, Department of Medicine, Emory University Atlanta, GA, USA.

ABSTRACT
Uncontrolled diabetes mellitus results in osmotic diuresis. Diabetic patients have lowered nitric oxide (NO) which may exacerbate polyuria. We examined how lack of NO affects the transporters involved in urine concentration in diabetic animals. Diabetes was induced in rats by streptozotocin. Control and diabetic rats were given L-NAME for 3 weeks. Urine osmolality, urine output, and expression of urea and water transporters and the Na-K-2Cl cotransporter were examined. Predictably, diabetic rats presented with polyuria (increased urine volume and decreased urine osmolality). Although metabolic parameters of control rats were unaffected by L-NAME, treated diabetic rats produced 30% less urine and osmolality was restored. UT-A1 and UT-A3 were significantly increased in diabetic rat inner medulla. While L-NAME treatment alone did not alter UT-A1 or UT-A3 abundance, absence of NO prevented the upregulation of both transporters in diabetic rats. Similarly, AQP2 and NKCC2 abundance was increased in diabetic animals however, expression of these transporters were unchanged by L-NAME treatment of diabetes. Increased expression of the concentrating transporters observed in diabetic rats provides a compensatory mechanism to decrease solute loss despite persistent glycosuria. Our studies found that although diabetic-induced glycosylation remained increased, total protein expression was decreased to control levels in diabetic rats treated with L-NAME. While the role of NO in urine concentration remains unclear, lowered NO associated with diabetes may be deleterious to the transporters' response to the subsequent osmotic diuresis.

No MeSH data available.


Related in: MedlinePlus

Upregulation of UT-A3 in diabetes is blunted by NO inhibition. Presented is a representative western blot of IM tip (A) probed for UT-A3. Densitometry was determined for all the 65-kDa smear (B) and 45-kDa glyco-form (C) in the IM tip. The experimental conditions were performed five times (n = 5) where there were five animals per experimental group in each cohort. In total, 25 animals per experimental group were analyzed. *p < 0.05 compared to control, †p < 0.05 compared to DM.
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Figure 2: Upregulation of UT-A3 in diabetes is blunted by NO inhibition. Presented is a representative western blot of IM tip (A) probed for UT-A3. Densitometry was determined for all the 65-kDa smear (B) and 45-kDa glyco-form (C) in the IM tip. The experimental conditions were performed five times (n = 5) where there were five animals per experimental group in each cohort. In total, 25 animals per experimental group were analyzed. *p < 0.05 compared to control, †p < 0.05 compared to DM.

Mentions: UT-A3 is also a glycoprotein that is found predominantly in the papilla in the IM. This transporter is distinguished as multiple glyco-forms ranging from 45- to 65-kDa (Blount et al., 2008) as detected in control rats (Figure 2A). Rats treated with l-NAME did not demonstrate a change in UT-A3 glycoprotein abundance (Figures 2B,C). Corroborating previous reports (Blount et al., 2008), UT-A3 abundance was increased in DM rats (Figure 2B). The increased protein abundance of UT-A3 is due to increased glycosylation of the upper form of the protein (Figure 2B) whereas induction of diabetes had no effect on the 45-kDa UT-A3 (Figure 2C). l-NAME treatment of the DM rats prevented the compensatory increase in UT-A3 abundance (Figure 2). Interestingly, l-NAME treatment of diabetic rats significantly reduced the 45-kDa glycosylated form of UT-A3 (Figure 2C).


The role of nitric oxide in the dysregulation of the urine concentration mechanism in diabetes mellitus.

Cipriani P, Kim SL, Klein JD, Sim JH, von Bergen TN, Blount MA - Front Physiol (2012)

Upregulation of UT-A3 in diabetes is blunted by NO inhibition. Presented is a representative western blot of IM tip (A) probed for UT-A3. Densitometry was determined for all the 65-kDa smear (B) and 45-kDa glyco-form (C) in the IM tip. The experimental conditions were performed five times (n = 5) where there were five animals per experimental group in each cohort. In total, 25 animals per experimental group were analyzed. *p < 0.05 compared to control, †p < 0.05 compared to DM.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368392&req=5

Figure 2: Upregulation of UT-A3 in diabetes is blunted by NO inhibition. Presented is a representative western blot of IM tip (A) probed for UT-A3. Densitometry was determined for all the 65-kDa smear (B) and 45-kDa glyco-form (C) in the IM tip. The experimental conditions were performed five times (n = 5) where there were five animals per experimental group in each cohort. In total, 25 animals per experimental group were analyzed. *p < 0.05 compared to control, †p < 0.05 compared to DM.
Mentions: UT-A3 is also a glycoprotein that is found predominantly in the papilla in the IM. This transporter is distinguished as multiple glyco-forms ranging from 45- to 65-kDa (Blount et al., 2008) as detected in control rats (Figure 2A). Rats treated with l-NAME did not demonstrate a change in UT-A3 glycoprotein abundance (Figures 2B,C). Corroborating previous reports (Blount et al., 2008), UT-A3 abundance was increased in DM rats (Figure 2B). The increased protein abundance of UT-A3 is due to increased glycosylation of the upper form of the protein (Figure 2B) whereas induction of diabetes had no effect on the 45-kDa UT-A3 (Figure 2C). l-NAME treatment of the DM rats prevented the compensatory increase in UT-A3 abundance (Figure 2). Interestingly, l-NAME treatment of diabetic rats significantly reduced the 45-kDa glycosylated form of UT-A3 (Figure 2C).

Bottom Line: We examined how lack of NO affects the transporters involved in urine concentration in diabetic animals.UT-A1 and UT-A3 were significantly increased in diabetic rat inner medulla.Our studies found that although diabetic-induced glycosylation remained increased, total protein expression was decreased to control levels in diabetic rats treated with L-NAME.

View Article: PubMed Central - PubMed

Affiliation: Renal Division, Department of Medicine, Emory University Atlanta, GA, USA.

ABSTRACT
Uncontrolled diabetes mellitus results in osmotic diuresis. Diabetic patients have lowered nitric oxide (NO) which may exacerbate polyuria. We examined how lack of NO affects the transporters involved in urine concentration in diabetic animals. Diabetes was induced in rats by streptozotocin. Control and diabetic rats were given L-NAME for 3 weeks. Urine osmolality, urine output, and expression of urea and water transporters and the Na-K-2Cl cotransporter were examined. Predictably, diabetic rats presented with polyuria (increased urine volume and decreased urine osmolality). Although metabolic parameters of control rats were unaffected by L-NAME, treated diabetic rats produced 30% less urine and osmolality was restored. UT-A1 and UT-A3 were significantly increased in diabetic rat inner medulla. While L-NAME treatment alone did not alter UT-A1 or UT-A3 abundance, absence of NO prevented the upregulation of both transporters in diabetic rats. Similarly, AQP2 and NKCC2 abundance was increased in diabetic animals however, expression of these transporters were unchanged by L-NAME treatment of diabetes. Increased expression of the concentrating transporters observed in diabetic rats provides a compensatory mechanism to decrease solute loss despite persistent glycosuria. Our studies found that although diabetic-induced glycosylation remained increased, total protein expression was decreased to control levels in diabetic rats treated with L-NAME. While the role of NO in urine concentration remains unclear, lowered NO associated with diabetes may be deleterious to the transporters' response to the subsequent osmotic diuresis.

No MeSH data available.


Related in: MedlinePlus