Tubuloglomerular feedback in Dahl rats.
We have previously demonstrated a loss of autoregulation in Dahl salt-sensitive (Dahl-S) rats rendered hypertensive on a high-salt diet. To determine whether this was due to a decreased activity of either the myogenic or the tubuloglomerular feedback (TGF) response, we tested the TGF response in both Dahl-S and salt-resistant Dahl rats on high- and low-salt diets. TGF was investigated in the closed-loop mode with a videometric technique, in which the response in late proximal flow rate to perturbations in Henle flow rate was measured. All Dahl rats showed a similar compensatory response to perturbations around the natural operating point, with a TGF response that was more efficient than in normotensive Sprague-Dawley rats. No evidence of decreased TGF responsiveness in hypertensive Dahl-S rats was found. The results suggest that the loss of autoregulation in hypertensive Dahl-S rats is due to a compromised myogenic response. We also measured the free-flow proximal intratubular pressure in Dahl rats. Perfectly regular oscillations were demonstrated in all Dahl series, including the hypertensive Dahl-S rats. This is the first demonstration of regular oscillations in an experimental rat model of hypertension.
Karlsen
F M
FM
Department of Medical Physiology, The Panum Institute, University of Copenhagen, DK-2200 Copenhagen, Denmark.
Leyssac
P P
PP
Holstein-Rathlou
N H
NH
D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D004039:Diet, Sodium-Restricted; D004351:Drug Resistance / Q000502:physiology; D005246:Feedback; D006706:Homeostasis / Q000502:physiology; D006874:Hydrostatic Pressure; D006973:Hypertension / Q000209:etiology / Q000503:physiopathology; D007678:Kidney Glomerulus / Q000503:physiopathology*; D007687:Kidney Tubules, Proximal / Q000503:physiopathology*; D008138:Loop of Henle / Q000503:physiopathology; D008297:Male; D051381:Rats; D020303:Rats, Inbred Dahl / Q000502:physiology*; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D012965:Sodium Chloride / Q000494:pharmacology*
D012965:Sodium Chloride