Denervated and intact kidney responses to saline load in awake and anesthetized dogs

The function of the innervated and denervated kidney was examined in clearance studies with unilaterally renal-denervated conscious and anesthetized dogs before and after saline loading. Barbiturate anesthesia distinctly depressed hemodynamics and excretory function of both kidneys and increased the difference between the denervated and innervated organ. In conscious moderately hydrated dogs the denervated kidney excreted slightly more sodium and water, while after saline loading higher excretion was observed on the innervated side. The denervated-to-innervated kidney ratios for UNaV, UNaV/100 ml GFR, and urine flow fell significantly from mean control values of 1.27, 1.27, and 1.20, respectively, to 0.80, 0.87, and 0.77 after extracellular volume expansion. Similar alterations of the ratios were observed in anesthetized dogs, but higher excretion of the denervated kidney persisted after saline loading. It is concluded that the greater natriuretic response of the intact kidney to saline infusion was due to inhibition of sodium-retaining action of renal efferent nerve activity by acute extracellular volume expansion.

Download Full-text

Effect of saline expansion on peritubule capillary pressures and reabsorption

AJP Renal Physiology ◽

10.1152/ajprenal.1981.240.2.f106 ◽

1981 ◽

Vol 240 (2) ◽

pp. F106-F110 ◽

Cited By ~ 1

Author(s):

C. E. Ott

Keyword(s):

Hydrostatic Pressure ◽

Volume Expansion ◽

Extracellular Volume ◽

Isotonic Saline ◽

Oncotic Pressure ◽

Capillary Uptake ◽

Before And After ◽

Dog Kidney ◽

Capillary Pressures ◽

Extracellular Volume Expansion

The effect of extracellular volume expansion on transcapillary Starling forces, capillary uptake, and the reabsorption coefficient in the peritubule microcirculation of the dog kidney was examined. Micropuncture techniques were used to obtain measurement before and after 4% body wt expansion with isotonic saline. Extracellular volume expansion significantly changed all Starling pressures and capillary uptake. Efferent arteriolar oncotic pressure, interstitial oncotic pressure, and capillary uptake decreased (33.1 +/- 3.3 to 22.1 +/- 4.1 mmHg; 5.2 +/- 0.4 to 4.0 +/- 0.3 mmHg; and 44.9 +/- 9.2 to 28.7 +/- 8.6 nl/min, respectively), whereas capillary hydrostatic pressure and interstitial hydrostatic pressure increased (11.3 +/- 1.2 to 13.7 +/- 1.4 and 5.9 +/- 1.0 to 10.4 +/- 1.2 mmHg, respectively). The calculated reabsorption coefficient was 2.40 during hydropenia and 2.36 nl . min-1 . mmHg-1 following volume expansion. The results show that extracellular volume expansion significantly depresses capillary uptake in the dog and suggest that the decreased uptake can be accounted for totally by changes in transcapillary pressures and a constant reabsorption coefficient.

Download Full-text

Electrolyte transport in remnant kidney of the dog: effect of furosemide

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1976.230.5.1231 ◽

1976 ◽

Vol 230 (5) ◽

pp. 1231-1238 ◽

Cited By ~ 2

Author(s):

SF Wen ◽

NL Wong ◽

RL Evanson ◽

EA Lockhart ◽

JH Dirks

Keyword(s):

Volume Expansion ◽

Extracellular Volume ◽

Stage Ii ◽

Stage Iii ◽

Contralateral Kidney ◽

Before And After ◽

Extracellular Volume Expansion ◽

Potassium Response ◽

Furosemide Administration ◽

Remnant Kidney

Micropuncture studies were performed in 26 dogs with a unilateral remnant kidney to examine its response to modest extracellular volume expansion and furosemide administration in the presence (Stage II) and absence (Stage III) of an intact contralateral kidney. During hydropenia in 15 Stage II dogs, proximal and distal transport of sodium and potassium was comparable to that of normal dogs (Stage I). Following 3% volume expansion, fractional proximal reabsorption was reduced similarly in Stages I and II. Although a slightly greater reduction in fractional loop reabsorption of sodium in Stage II after volume expansion was not significant, it was significantly greater with furosemide administration. In 11 Stage III dogs, proximal fractional reabsorption was depressed during hydropenia, and the loop sodium response to both volume expansion and furosemide administration was exaggerated. In contrast, greater increase in distal potassium secretion was demonstrated mainly in Stage III but not in Stage II remnant kidneys both before and after the diuretic maneuvers. The observations of exaggerated sodium response to furosemide by the remnant kidney in both Stages II and III but greater potassium response only in Stage III suggest that independent factors are responsible for these adaptations when functioning renal mass is reduced.

Download Full-text

Effect of volume expansion on renal glucose transport in normal and uremic dogs

AJP Renal Physiology ◽

10.1152/ajprenal.1979.236.6.f567 ◽

1979 ◽

Vol 236 (6) ◽

pp. F567-F574

Author(s):

S. F. Wen ◽

R. W. Stoll

Keyword(s):

Volume Expansion ◽

Extracellular Volume ◽

Distal Tubule ◽

Proximal Convoluted Tubule ◽

Glucose Reabsorption ◽

Urinary Glucose ◽

Before And After ◽

Intermediate Segment ◽

Extracellular Volume Expansion ◽

Remnant Kidney

Proximal and distal tubule micropuncture studies were performed in normal and uremic remnant-kidney dogs to examine the tubule mechanism of glucose reabsorption before and after 10% extracellular volume expansion. In normal dogs volume expansion markedly inhibited glucose reabsorption in the proximal convoluted tubule, but the ensuing increase in further distal glucose delivery was nearly completely reabsorbed in the intermediate segment (between late proximal tubule and distal tubule). In the uremic, remnant-kidney dogs, glomerulotubular balance for glucose was well maintained in the proximal convoluted tubule despite an adaptive increase in nephron filtration rate. Volume expansion markedly increased glucose delivery out of the proximal convoluted tubule and an incomplete glucose reabsorption in the intermediate segment led to glycosuria. When glucose delivery to the intermediate segment was increased to a comparable degree by subthreshold glucose loading in hydropenic normal dogs, glucose reabsorption in this segment was virtually complete, suggesting that in the volume-expanded uremic dogs glucose reabsorptive capacity in the intermediate segment was reduced. Thus, the intermediate segment appears to play a significant role in the fine regulation of urinary glucose excretion.

Download Full-text

Acute unilateral renal denervation in rats with extracellular volume expansion

AJP Renal Physiology ◽

10.1152/ajprenal.1977.232.1.f26 ◽

1977 ◽

Vol 232 (1) ◽

pp. F26-F32 ◽

Cited By ~ 7

Author(s):

E. Bello-Reuss ◽

E. Pastoriza-Munoz ◽

R. E. Colindres

Keyword(s):

Volume Expansion ◽

Renal Denervation ◽

Renal Plasma Flow ◽

Left Kidney ◽

Extracellular Volume ◽

Urine Volume ◽

Urinary Sodium Excretion ◽

Sodium Reabsorption ◽

Before And After ◽

Extracellular Volume Expansion

Sodium reabsorption along the nephron was studied before and after acute unilateral denervation of the left kidney in anesthetized rats with extracellular volume expansion. Studies were also performed before and after sham denervation. Denervation increased urine volume (V) from the left kidney from 35.2 to 59.2 mul min-1 (P less than 0.001) and urinary sodium excretion (UNaV) from 6.9 to 11.8 mueq min-1 (P less than 0.001). The control right kidney showed a simultaneous 45% decrease in V and UNaV. Inulin clearance (GFR) and renal plasma flow (RPF) remained unchanged after denervation in both kidneys. Left kidney late proximal (F/P)m decreased from 1.50 to 1.24 (P less than 0.01); single-nephron GFR (SNGFR) remained unchanged. (F/P)m ratios were also decreased in early distal (3.87–2.65, P less than 0.005) and late distal (5.48–3.83, P less than 0.02) convolutions. Fractional and absolute Na reabsorption in the distal convolution did not decrease. GFR, RPF, V, UNa, late proximal (F/P)m, and SNGFR were unchanged in shamdenervated rats. The increases in V and UNa V produced by acute renal denervation in the volume-expanded anesthetized animal are thus caused by further depression of proximal tubular salt and water reabsorption.

Download Full-text