title: Acute arterial hypertension inhibits proximal tubular fluid reabsorption in normotensive rat but not in SHR.
abstract: The effect of acute arterial hypertension on proximal tubular fluid reabsorption was investigated in Sprague-Dawley rats and spontaneously hypertensive rats (SHR) by measuring proximal tubular flow with a nonobstructive optical method. Under control conditions, spontaneous tubular flow was oscillating at 0.02-0.03 Hz in Sprague-Dawley rats. Acute hypertension induced an immediate increase of mean tubular flow (50% increase after 20 min of hypertension) and augmentation of oscillatory amplitude. Acute hypertension did not alter single-nephron blood flow as measured by laser-Doppler velocimetry (n = 12), suggesting that the increase of tubular flow was due to inhibition of reabsorption but not increase of filtration. By contrast, spontaneous tubular flow was fluctuating aperiodically in SHR. Acute hype tension did not induce a continuous increase of tubular flow or an increase in amplitude of fluctuations (n = 15). When apical Na(+)/H(+) exchange activity of proximal tubule was monitored, acute hypertension did not alter the activity in SHR (n = 8), while similar procedures had been shown to inhibit apical Na(+)/H(+) exchange activity of proximal tubules by more than 40% in Sprague-Dawley rats. These observations suggest that acute hypertension inhibits proximal tubular fluid reabsorption by inhibiting apical Na(+)/H(+) exchange activity in Sprague-Dawley rats and that this mechanism is impaired in SHR.
authors.affiliation: Department of Physiology and Biophysics, College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., Tampa, FL 33612, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Walstead
authors.forename: Kay-Pong
authors.initials: KP
authors.lastname: Yip
mesh_terms: D000042:Absorption; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D006973:Hypertension / Q000235:genetics / Q000503:physiopathology*; D007687:Kidney Tubules, Proximal / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D009399:Nephrons / Q000098:blood supply; D051381:Rats; D011918:Rats, Inbred SHR; D017207:Rats, Sprague-Dawley; D012079:Renal Circulation / Q000502:physiology; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D014655:Vascular Resistance / Q000502:physiology
chemical_list: D017923:Sodium-Hydrogen Exchangers