Renal functional reserve in treated and untreated hypertensive rats.
Renal functional reserve (renal response to protein loading, RFR) has been suggested as a method to verify the presence of hyperfiltration. This study was designed to evaluate the role of RFR as an indicator of increased glomerular capillary hydrostatic pressure in short-term treated and untreated rats with two-kidney, one-clip Goldblatt hypertension. One month after placing a silver clip, micropuncture studies were performed on the unclipped kidney. Normal rats and three groups of clipped rats [untreated group (HYP), a group treated with captopril (CEI) and a group treated with verapamil (VER) 5 days before the micropuncture studies] were studied. Glomerular hemodynamics and proximal tubular reabsorption were measured in control period and during intravenous administration of glycine (G). In normal rats, G produced afferent and efferent dilation, increases in single nephron plasma flow (SNPF) and single nephron glomerular filtration rate (SNGFR) of 24%. Systemic hypertension in HYP rats was associated with increases in transcapillary pressure gradient (delta P) and SNGFR. In this hyperfiltration state, infusion of G did not modify SNGFR of SNPF defining loss of RFR. The antihypertensive treatment was equally effective in normalizing MAP and delta P in CEI and VER, but only CEI rats responded to G with a 20% increase in SNGFR due to an increase in delta P. The most striking findings were that loss of RFR in both HYP and VER rats was associated with a significant decrease in absolute and proximal fractional reabsorption.(ABSTRACT TRUNCATED AT 250 WORDS)
De Nicola
L
L
Division of Nephrology-Hypertension, University of California, San Diego School of Medicine.
Blantz
R C
RC
Gabbai
F B
FB
D000818:Animals; D002216:Captopril / Q000627:therapeutic use; D005998:Glycine / Q000008:administration & dosage / Q000097:blood; D006978:Hypertension, Renovascular / Q000188:drug therapy / Q000503:physiopathology*; D007677:Kidney Function Tests; D007678:Kidney Glomerulus / Q000503:physiopathology*; D008297:Male; D011677:Punctures; D051381:Rats; D011919:Rats, Inbred Strains; D012079:Renal Circulation; D014700:Verapamil / Q000627:therapeutic use
D002216:Captopril; D014700:Verapamil; D005998:Glycine