ISSN:
1432-2013
Keywords:
d-Glucose
;
Tubular Transport
;
Glomerulotubular balance
;
Micropuncture
;
Clearance
;
Rat
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract d-Glucose transport in the kidney of glucose loaded rats was investigated using clearance and micropuncture techniques. The range of plasma glucose concentration in clearance experiments was 20–140 mmol·l−1 and in micropuncture experiments 17–94 mmol·l−1. 1. During hyperglycemia, the glucose concentration in endproximal tubular fluid was elevated above that in arterial plasma. At plasma concentrations above 60 mmol l−1 intratubular glucose concentration was found to be about 1.2 times higher than in plasma. 2. At endproximal puncture sites TF/Posmol was unity throughout the investigated range of hyperglycemia. 3. Proximal tubular glucose reabsorption during hyperglycemia is close to saturation which is compatible to aK m=10.8 mmol l−1 as determined previously. 4. Passive glucose permeability does not change during hyperglycemia. The permeability constant of 2.03·10−5 cm·s−1 does not differ significantly from that during normoglycemia, 1.9·10−5 cm·s−1. 5. Single nephron glomerular filtration rate (SNGFR) and fluid reabsorption in the proximal convolution (C) were significantly correlated during hyperglycemia (r=0.78,P〈0.001). Fractional volume reabsorption during hyperglycemia was decreased to 0.36 as compared to control, but during hyperglycemia it was not affected by the magnitude of the glucose plasma concentration. 6. During hyperglycemia, proximal tubular glucose reabsorption (TG) was correlated to SNGFR (r=0.64,P〈0.001). This relation became insignificant when the influence of volume reabsorption (C) is controlled for (r=0.17,P〉0.5). However, the significance of the correlation between TG and C persists when the influence of SNGFR is held constant. 7. Calculations indicate that when glucose reabsorption was doubled, et sodium transport was increased about fourfold. 8. In hyperglycemia, renal transport rate (TG), when factored by renal glomerular filtration rate (GFR) seems to be linearly related to glucose plasma concentration. Up to endproximal puncture site 25.5% and by the entire kidney 68.2% of the tubular glucose load were reabsorbed. The difference may be attributed either to glucose transport systems which are localized distal to the proximal convoluted tubules and/or to an inhomogenity of the glucose transport in the different types of nephrons.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00589512
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