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Natriuretic response to renal medullary endothelin B receptor activation is impaired in Dahl‐salt sensitive rats on a high‐caloric diet
Author(s) -
Kittikulsuth Wararat,
Zhang Yawen,
Sunjic Igor,
Pollock David M.
Publication year - 2012
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.26.1_supplement.1069.9
Subject(s) - endocrinology , medicine , chemistry , diuretic , excretion , urine flow rate , renal function , endothelin receptor , kidney , natriuresis , receptor
Renal medullary endothelin B receptors (ET B ) mediate sodium excretion and blood pressure (BP) control. Several animal models of hypertension including the Dahl salt sensitive (DS) rat on a high salt diet have impaired renal medullary endothelin system. Our lab has recently reported that the DS rat becomes hypertensive on a normal salt, high‐caloric diet. Thus we hypothesized that renal medullary ET B function is dysfunctional in DS rats fed a high‐caloric diet. The diuretic and natriuretic response to intramedullary infusion of ET B agonist sarafotoxin 6c (S6c) was determined in DS rats fed either a normal (14% fat; 3.93 kcal/g) or high‐caloric diet (59% fat; 5.45 kcal/g) for 4 weeks. We found that 4‐week high‐caloric diet elevated systolic BP in DS rats (126±2 vs. 143±3 mmHg, p<0.05). In DS rats fed a regular diet, intramedullary infusion of S6c (0.45 μg/kg/hr) increased urine flow (3.6±0.5 μl/min during baseline vs. 7.0±0.5 μl/min after S6c; p<0.05) and sodium excretion (0.42±0.09 vs. 0.97±0.08 μmol/min; p<0.05). However, DS rats fed a high‐caloric diet did not display an increase in urine flow (2.8±0.3 vs. 4.3±0.5 μl/min) or sodium excretion (0.35±0.07 vs. 0.48±0.12 μmol/min) upon S6c infusion. These data demonstrate that renal medullary ET B function is impaired in DS rats fed a high‐caloric diet, which may contribute to the elevation of blood pressure during high‐caloric feeding in this model.