Changes in glomerular hemodynamic response to angiotensin II after subacute renal denervation in rats

Abstract

We examined the changes in glomerular hemodynamics produced by angiotensin II (AII) in both normal Munich-Wistar rats and rats which were unilaterally renal denervated (measured kidney) 4-6 d prior to the measurement periods. Measurements of glomerular dynamics were performed in a control period after plasma volume expansion and during infusion of 11 ng · 100 g body wt-1 · min-1 of AII. The glomerular hydrostatic pressure gradient increased from 38 ± 1 to 49 ± 1 mmHg in denervated rats compared with a lesser response in controls (from 39 ± 1 to 45 ± 1 mmHg, P < 0.05). Single nephron plasma flow decreased from 213 ± 17 to 87 ± 4 nl · min-1 · g kidney wt (KW)-1 in denervated kidneys versus a more modest decrease in control kidneys (from 161 ± 9 to 102 ± 5 nl · min · gKW-1). These changes were due to a greater increase in both afferent and efferent arteriolar resistance after AII infusion in denervated compared with control kidneys. Glomerular AII receptor maximum binding was 1,196 ± 267 fmol/mg protein in denervated kidneys compared with 612 ± 89 fmol/mg protein (P < 0.01) in controls with no change in receptor affinity. We conclude the subacute unilateral renal denervation (a) results in renal vasodilation, (b) denervation magnifies the vasoconstrictive effect of AII infusion on glomerular hemodynamics, and (c) the observed increased response to AII after denervation is associated with increases in glomerular AII receptors.