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  • 1
    ISSN: 1432-2013
    Keywords: Rat ; Renal function ; Micropuncture ; Blood gases ; Anaesthesia ; Thiopentone ; Thiobutabarbitone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The thiobutabarbitone(TB, Inactin)-anaesthetised rat is an extremely widely used preparation for the study of renal function at the whole-organ and nephron levels. The recent withdrawal of TB from the market has made it essential to find an anaesthetic producing experimental conditions as similar as possible to TB to allow comparison of past and future data. Blood gas analysis, clearance and micropuncture studies were therefore performed in rats anaesthetised with TB or the related thiobarbiturate thiopentone (TP) (both 100 mg/ kg body weight) to establish whether the latter meets this requirement. Both barbiturates caused similar transient respiratory depression and acidosis. Mean values (TP versus TB) over the total 8-h observation period for glomerular filtration rate (0.94 versus 1.05 ml/min), urine flow (3.8 versus 4.4 μl/min) and K+ excretion (0.98 versus 1.18 μmol/min) were slightly lower (P〈0.05) in TP rats, whereas renal blood flow (6.26 versus 6.24 ml/min), filtration fraction (0.31 versus 0.34) and Na+ excretion (0.11 versus 0.098 μmol/min) did not differ. The single-nephron filtration rate (SNGFR) (42.1 versus 41.1 nl/min) and fractional reabsorption (42% versus 47%), both measured in the proximal tubule, did not differ, although in the TP group SNGFR rose with time (4.4%/h) whereas the fractional reabsorption did not change significantly; in the TB group SNGFR was constant but fractional reabsorption declined with time (1.5%/h). Fractional reabsorption up to the distal convoluted tubule declined with time, this was more pronounced in the TP group. SNGFR measured at this site did not differ between TP and TB (30.3 versus 30.1 nl/min) but increased with time with TP (2.7%/h). Although renal function under TP is somewhat less stable than under TB, the differences are minor and, given that the latter is also characterised by non-steady-state conditions, it is concluded that TP is a reasonable replacement for TB.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 306 (1979), S. 287-293 
    ISSN: 1432-1912
    Keywords: 2.4-diamino-6.7-dialkylpteridine ; Diuretics ; Micropuncture ; Tubular transport ; Rat kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The excretion of the diuretic substance DADMP (2.4-diamino-6.7-dimethylpteridine) and of DMP (6.7-dimethylpterin) was studied on single nephrons of the rat kidney using microperfusion and microinjection techniques. In the proximal tubule only DADMP was reabsorbed to a significant degree. Fractional reabsorption rate was independent of the load applied and the permeability constant was found to be 2.2·10−4 cm·s−1. Similar results were obtained in nephrons in which the substances, with inulin, were injected from middle proximal tubular puncture sites and recovered in the urine. DMP appeared in the urine quantitatively and simultaneously with the injected inulin. DADMP recovery, however, was only 20–30% of the injected load during the injection period and after 2 h some 70% was recovered from the urine of both kidneys. The reabsorbed fractions were independent of the loads applied, which varied between 2·10−13 mol·min−1 and 10−9 mol·min−1. A comparison of the microperfusion and the microinfusion data suggests that the reabsorption of DADMP occurs predominantly in the proximal convolution, and it appears that the differences between the renal handling of DMP and DADMP are explicable by their different lipid solubilities.
    Type of Medium: Electronic Resource
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