ISSN:
1432-1912
Keywords:
Aminoglycoside
;
Gentamicin
;
Kidney
;
Electron microscopic autoradiography
;
Lysosomes
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Upon intravenous injection of 3H-gentamicin in rats, radioactivity in serum rapidly declined to 3% of total within 1 h. Kidneys accumulated a constant amount (14%) of the injected radioactivity between 2 and 6 h after injection. In mice, simultaneous or prior application of unlabeled gentamicin (10 mg/kg) diminished the renal concentration of 3H-gentamicin, and aprotinin (10 mg/kg) was able to compete with labeled aprotinin. Aprotinin did not diminish the renal accumulation of gentamicin and vice versa. However, since 10 mg/kg aprotinin raised also the plasma concentrations of both 3H-gentamicin and 125I-aprotinin, the evidences resulting from these experiments are limited. Mouse kidney cortex was processed for light and electron microscopic autoradiography at different times following i.v. injection of 3H-gentamicin. Gentamicin enters the apical part of proximal tubule cells. Initially, brush border and basement membrane labeling is prominent, whereas lysosomes appear as intense and prevalent stores 20 min or later after injection. Fractionation of 3H-gentamicin loaded kidneys showed a similar distribution pattern of radioactivity and the lysosomal marker β-galactosidase. The same was true when the crude lysosomal fraction was subjected to density gradient centrifugation, which corroborates the microscopical findings. Radioactivity is partially bound to lysosomal structures, for repeated freezing of loaded lysosomes left 35% of radioactivity particle-bound. It is concluded that both gentamicin and peptides are handled in a similar manner by adsorption, followed by endocytosis and lysosomal sequestration in proximal tubule cells.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00505080
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