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Enalapril Treatment Restores the Attenuated Proximal Tubule Reabsorption in Response to Acute Volume Expansion (VE) in Diabetic Rats
Author(s) -
Khraibi Ali A.,
Yu Tianzheng
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a343-b
Subject(s) - reabsorption , enalapril , proximal tubule , medicine , endocrinology , chemistry , kidney , angiotensin converting enzyme , blood pressure
The natriuretic and diuretic responses to an acutely administered saline load are reduced in diabetes mellitus and these altered responses are associated with sodium retention. Inhibition of the renin‐angiotensin‐system (RAS) has renoprotective and cardiovascular protective effects. The objective of this study was to determine the roles of proximal tubule reabsorption and the RAS in the attenuated natriuretic and diuretic responses to VE in diabetic rats (DC, n=12). Fractional excretions of phosphate (FE Pi ) and lithium (FE Li ) were utilized as indexes for proximal tubule reabsorption. VE significantly increased both FE Li and FE Pi in all groups of rats. However, the increased FE Li and FE Pi in DC rats (ΔFE Li =17.26±4.69% and ΔFE Pi =7.38±2.9%) were significantly lower as compared with those in nondiabetic control rats (NC, n=8; Δ FE Li =32.15±5.03% and ΔFE Pi =20.62±3.5%). The lower increases in FE Li and FE Pi are associated with an attenuated increase in renal interstitial hydrostatic pressure (ΔRIHP) in DC (1.8±0.5 mmHg) compared with NC rats (4.3±0.4 mmHg). Enalapril treatment (25 mg/kg/day in drinking water) had no effect on nondiabetic rats (NE, n=8) as compared with untreated NC rats, but significantly improved RIHP response (ΔRIHP) to VE in diabetic rats (DE, 2.8± 0.6 mmHg). Both ΔFE Li and FE Pi were restored by enalapril treatment in diabetic rats and no significant differences were found in ΔFE Li and ΔFE Pi between DE (ΔFE Li =26.81±5.24% and ΔFE Pi =10.45±4.95%) and NC groups of rats in response to VE. These data suggest that RAS and RIHP may play an important role in the attenuated inhibition of proximal tubule reabsorption in response to acute saline volume expansion in diabetic rats.