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ET B Receptors in High Salt Diet‐Induced Decline of Renal Autoregulation in Rats
Author(s) -
Guan Zhengrong,
Pollock David,
Inscho Edward
Publication year - 2015
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.29.1_supplement.808.8
Subject(s) - autoregulation , medicine , endocrinology , renal blood flow , chemistry , blood pressure , perfusion , receptor , mean arterial pressure , endothelin receptor , renal function , kidney , heart rate
High salt (HS) diet is linked to increased endothelin‐1 (ET‐1) and salt‐dependent hypertension. Previous studies showed that HS treatment increased renal microvascular ET B receptor expression and impaired renal blood flow (RBF) autoregulation. We hypothesized that HS leads to a decline of renal autoregulation via activation of ET B receptors. RBF autoregulation was assessed in anesthetized ET B deficient (ET B ) and intact control littermates (Con) rats fed normal salt (NS) or HS (8% NaCl) for 2 weeks. RBF was monitored using an ultrasonic flow probe and autoregulation was assessed during step‐decrements of arterial pressure imposed using an aortic occluder placed between the two renal arteries. ET B deficient rats (n=6) exhibited significantly elevated baseline mean arterial pressure (MAP, 132±5 vs. 116±1 mmHg in Con+NS, n=8, P<0.05). HS did not change MAP in either group but significantly increased RBF in Con rats (n=8, 12.5±0.7 vs. 9.2±0.5 ml/min.gkw in Con+NS, P<0.05) while decreasing RBF in ET B rats (6.8±0.6 ml/min.gkw vs. Con+NS, P<0.05). HS led to attenuated autoregulation of RBF in Con rats. Decreasing renal perfusion pressure from ambient to 95 mmHg resulted in an 11±2% decrease in RBF in Con+HS versus a 3±1% in Con+NS (P<0.05). Accordingly, autoregulatory index (AI) was 0.63±0.08 in Con+HS versus 0.18±0.09 in Con+NS (P<0.05). In contrast, RBF remained fairly stable in ET B +NS and ET B +HS rats during a stepwise reduction of renal perfusion pressure from ambient to 95 mmHg. AI averaged 0.26±0.14 and 0.12±0.24, respectively, suggesting intact autoregulation in ET B deficient rats. These data suggest that HS leads to attenuated RBF autoregulation and increased RBF via ET B receptoractivation.