Renal responses to hypertonic saline infusion in salt-sensitive spontaneously hypertensive rats.
In Wistar Kyoto (WKY) and Sprague Dawley rats, high dietary sodium chloride (NaCl) increases natriuretic and diuretic responses to acute isotonic saline infusion, but in NaCl-sensitive spontaneously hypertensive rats (SHR-S), a high-NaCl diet causes negligible increases in natriuretic and diuretic responses. To investigate whether this deficit in sodium and fluid excretion in SHR-S is stimulus (volume)-specific or because of a more generalized alteration in renal function, the present study measured, in SHR-S and Wistar Kyoto rats, natriuretic and diuretic responses to a hypertonic saline infusion (the amount of sodium infused was equal to that infused in a previous, isotonic experiment). Eight-week-old Wistar Kyoto rats, SHR-S, and salt-resistant SHR were given a basal (1%) or high (8%)-NaCl diet for 2 weeks. Intravenous infusion of hypertonic saline increased mean arterial pressure and reduced heart rate in all groups. Baseline sodium excretion was lower in SHR-S compared with salt-resistant SHR with either diet, but after infusion of hypertonic saline, all 6 groups displayed significant increases in sodium and fluid excretion, glomerular filtration rate, and effective renal blood flow (ERBF). The percent-sodium excretion in response to hypertonic saline infusion was slightly, but significantly, lower in SHR-S (compared with salt-resistant SHR) for either the basal or the high-NaCl diet. We conclude that renal responses to hypertonic saline infusion are affected minimally in SHR-S compared with salt-resistant SHR or Wistar Kyoto rats. Therefore, the deficits in renal function observed in SHR-S after volume loading are not reflected in a renal deficit to hypertonic saline challenge.
Mozaffari
M S
MS
Department of Oral Biology/Pharmacology, School of Dentistry, Medical College of Georgia, Augusta 30912-1128, USA.
Roysommuti
S
S
Shao
Z H
ZH
Wyss
J M
JM
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004231:Diuresis / Q000187:drug effects*; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000503:physiopathology*; D007262:Infusions, Intravenous; D007668:Kidney / Q000503:physiopathology*; D008297:Male; D009318:Natriuresis / Q000187:drug effects*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017597:Renal Blood Flow, Effective / Q000187:drug effects; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage / Q000494:pharmacology*; D012964:Sodium / Q000652:urine; D012982:Sodium, Dietary / Q000008:administration & dosage*
D012462:Saline Solution, Hypertonic; D012982:Sodium, Dietary; D012964:Sodium