Effects of glucose on water and sodium reabsorption in the proximal convoluted tubule of rat kidney.

SUMMARY1. In rats receiving 200 gl. min-sodium chloride, glomerular filtration rate, single nephron glomerular filtration rate, and fractional reabsorption were measured at various points along the nephron, and ionic concentrations measured in early distal tubular fluid in virgin and 6, 12 and 19 day pregnant rats.2. Glomerular filtration increased progressively until the twelfth day ofpregnancy. At 19 days of pregnancy the glomerular filtration rate, while still above virgin levels, was reduced below 12 day pregnant levels.3. Single nephron glomerular filtration rates measured in proximal and distal tubules were different at both 12 and 19 days of pregnancy, indicating an alteration of tubuloglomerular feed-back. 4. A change in the ratio ofglomerular filtration rate: distal single nephron filtration rate indicated a redistribution of glomerular filtrate to juxtamedullary nephrons by the sixth day of pregnancy.5. Fluid reabsorption is similar up to the early distal tubule but it is not possible to say whether reabsorption is the same in proximal tubules. More fluid is reabsorbed by late distal tubules and collecting ducts in 12 and 19 day pregnant animals than in the virgin and 6 day pregnant animals.6. Changes in ion reabsorption by the loop of Henle occurred during pregnancy; sodium reabsorption was increased by the sixth day of pregnancy and potassium reabsorption by the twelfth day.

Section: Methodsmentioning

confidence: 99%

Micropuncture study of changes in glomerular filtration and ion and water handling by the rat kidney during pregnancy

Garland

Green

1982

“…Thus, while demonstrations of an effect of glucose on proximal transtubular potential difference (Kokko, 1973;Fr6mter & Gessner, 1974;Cardinal, Lutz, Burg & Orloff, 1975) have been interpreted in terms of an influence of glucose on sodium co-transport, such studies provide no information as to the quantitative significance of glucose-influenced sodium movement relative to total proximal tubular sodium reabsorption. Such information as is available from micropuncture experiments on rat kidney is inconsistent, and includes descriptions of a marked effect of glucose on proximal tubular reabsorption of fluid (Weinman, Suki & Eknoyan, 1976) and no significant effect Bishop, Green & Thomas, 1975, 1978.…”

Section: Introductionmentioning

confidence: 99%

Effects of phlorizin on glucose, water and sodium handling by the rat kidney.

Bishop¹,

Elegbe²,

Green³

et al. 1978

Self Cite

SUMMARY1. The effect of phlorizin on glucose, water and sodium handling by the kidney in anaesthetized rats was investigated, using clearance techniques, during infusion of saline (200 j1. min-') or saline to which either low (0 1 smole kg body weight-' ml.-') or high (1.0 molee kg body weight-' ml.-') doses of phlorizin had been added.2. Phlorizin increased the absolute and fractional excretion of glucose, urine osmolality and negative free water clearance; and reduced urine flow rate, glomerular filtration rate (GFR), absolute and fractional excretion of sodium, absolute excretion of sodium, absolute excretion of potassium and absolute and fractional rates of glucose reabsorption.3. The data indicate that phlorizin has sites of action and effects additional to those on glucose transport in the proximal tubule.4. Within each series there was a positive correlation between sodium and glucose reabsorption; but the rate of glucose reabsorption was different between each series even though the sodium reabsorption was not.5. It is suggested that since both sodium and glucose reabsorption correlate with GFR, they may be related via GFR.6. The data indicate that for the whole kidney any effect of glucose on sodium transport is small relative to total renal handling of sodium.

“…They were prepared for micropuncture as described previously (Bishop, Green & Thomas, 1978). Briefly, animals were anaesthetized by an i.P.…”

Section: Methodsmentioning

confidence: 99%

“…toluene, as a scintillant. Plasma and tubular fluid concentrations of sodium were measured on a Helium Flow Photometer (Aminco Inc., Silver Springs, Maryland, U.S.A.) and glucose was measured using an enzymatic technique (Bishop et al 1978) Results are presented as mean +s.E. of mean and the significance of differences are calculated using Student's t test.…”

Section: Analysesmentioning

confidence: 99%

Effects of pregnancy on glucose reabsorption by the proximal convoluted tubule in the rat.

Bishop¹,

Green²

1981

Self Cite

SUMMARY1. Free-flow micropuncture techniques were used to investigate glucose, sodium and water reabsorption along the proximal convoluted tubule in 7-8 day pregnant rats undergoing saline or glucose infusion and in virgin controls.2. Absolute proximal tubular reabsorption of glucose was greater in pregnant animals than virgins during both saline and glucose infusion; and fractional reabsorption of glucose was higher in pregnant than in virgin animals during glucose infusion.3. During glucose loading, less glucose escaped reabsorption in the proximal tubule in pregnant than in virgin animals. It is concluded that the increased excretion of glucose observed in pregnant rats cannot be due to failure of proximal tubular mechanisms.4. During saline infusion pregnant animals had a higher single nephron glomerular filtration rate (s.N.G.F.R.) when compared with virgin animals and a corresponding increase in reabsorption of sodium and water. The small increases in S.N.G.F.R. and sodium reabsorption in pregnant animals (compared with virgin animals) during glucose infusion were not statistically significant.5. Fractional reabsorption of sodium (and water) along the proximal convoluted tubule was not significantly different in the four series. It is concluded that glomerulo-tubular balance operates during pregnancy.