High-NaCl intake impairs dynamic autoregulation of renal blood flow in ANG II-infused rats.
The aim of this study was to investigate dynamic autoregulation of renal blood flow (RBF) in ANG II-infused rats and the influence of high-NaCl intake. Sprague-Dawley rats received ANG II (250 ng·kg(-1)·min(-1) sc) or saline vehicle (sham) for 14 days after which acute renal clearance experiments were performed during thiobutabarbital anesthesia. Rats (n = 8-10 per group) were either on a normal (NNa; 0.4% NaCl)- or high (HNa; 8% NaCl)-NaCl diet. Separate groups were treated with 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (tempol; 1 M in drinking water). Transfer function analysis from arterial pressure to RBF in the frequency domain was used to examine the myogenic response (MR; 0.06-0.09 Hz) and the tubuloglomerular feedback mechanism (TGF; 0.03-0.06 Hz). MAP was elevated in ANG II-infused rats compared with sham groups (P < 0.05). RBF in ANG II HNa was reduced vs. sham NNa and sham HNa (6.0 ± 0.3 vs. 7.9 ± 0.3 and 9.1 ± 0.3 ml·min(-1)·g kidney wt(-1), P < 0.05). transfer function gain in ANG II HNa was significantly elevated in the frequency range of the MR (1.26 ± 0.50 dB, P < 0.05 vs. all other groups) and in the frequency range of the TGF (-0.02 ± 0.50 dB, P < 0.05 vs. sham NNa and sham HNa). Gain values in the frequency range of the MR and TGF were significantly reduced by tempol in ANG II-infused rats on HNa diet. In summary, the MR and TGF components of RBF autoregulation were impaired in ANG II HNa, and these abnormalities were attenuated by tempol, suggesting a pathogenetic role for superoxide in the impaired RBF autoregulatory response.
Saeed
Aso
A
Dept. of Molecular and Clinical Medicine/Nephrology, Institute of Medicine, The Sahlgrenska Academy at Univ. of Gothenburg, Vita Stråket 12, Sahlgrenska Univ. Hospital, S-413 45 Gothenburg, Sweden. aso.saeed@vgregion.se.
Dibona
Gerald F
GF
Marcussen
Niels
N
Guron
Gregor
G
D000804:Angiotensin II / Q000008:administration & dosage*; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage; D001794:Blood Pressure / Q000187:drug effects; D003497:Cyclic N-Oxides / Q000008:administration & dosage; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006706:Homeostasis; D007279:Injections, Subcutaneous; D007668:Kidney / Q000098:blood supply* / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012079:Renal Circulation / Q000187:drug effects*; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage*; D013113:Spin Labels; D013481:Superoxides / Q000378:metabolism; D013997:Time Factors
D000975:Antioxidants; D003497:Cyclic N-Oxides; D017673:Sodium Chloride, Dietary; D013113:Spin Labels; D013481:Superoxides; D000804:Angiotensin II; C001803:tempol