Gentamicin inhibits renal protein and phospholipid metabolism in rats: Implications involving intracellular trafficking

D. P. Sundin, R. Sandoval, Bruce Molitoris

Research output: Contribution to journalArticle

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Abstract

Studies were undertaken to characterize the mechanism of aminoglycoside-induced nephrotoxicity. Early time points in gentamicin treatment (1 to 3 d) were used to investigate the development of toxic events without the complication of gross morphologic cellular alterations. Enzyme activities of cortical homogenates and brush border membrane (BBM) preparations documented little effect on specific activities or the ability to isolate representative membrane fractions. In vivo protein synthesis experiments demonstrated that gentamicin reduced cellular protein synthesis after 2 d of treatment. This inhibition increased to 50% on the third day. Total cellular protein synthesis was inhibited to the same extent as BBM protein synthesis. However, gentamicin had different effects on homogenate versus BBM phospholipids. The total phospholipid contents in cortical homogenates and BBM from treated animals were increased, compared with control animals. A significant decrease in phospholipid synthesis was observed only in homogenates from treated animals. When effects on individual phospholipids were investigated, only an increase in phosphatidylinositol levels was observed in cortical homogenates from treated rats. However, gentamicin treatment was demonstrated to increase the levels of phosphatidylinositol and phosphatidylcholine, while decreasing the level of sphingomyelin (SPH), in BBM. Incorporation of 32P into SPH, phosphatidylserine, and phosphatidylethanolamine was inhibited in cortical homogenates from gentamicin-treated animals; among BBM phospholipids, however, a significant decrease was observed only for SPH synthesis. It was concluded that inhibition of phospholipid degradation was quantitatively the major contributor to the effects of gentamicin on phospholipid metabolism. Confocal microscopic studies, using tracer amounts of fluorescently labeled gentamicin, revealed gentamicin in large, mostly basal structures. Correlative electron microscopic studies, using photo-oxidation techniques, demonstrated that these structures consisted of lysosomal, Golgi complex, and mitochondrial structures. These observations suggest retrograde trafficking of gentamicin and indicate a general mechanism of gentamicin-induced nephrotoxicity.

Original languageEnglish
Pages (from-to)114-123
Number of pages10
JournalJournal of the American Society of Nephrology
Volume12
Issue number1
StatePublished - 2001

Fingerprint

Gentamicins
Phospholipids
Kidney
Microvilli
Proteins
Membranes
Sphingomyelins
Phosphatidylinositols
Poisons
Phosphatidylserines
Golgi Apparatus
Aminoglycosides
Phosphatidylcholines
Membrane Proteins
Electrons
Enzymes

ASJC Scopus subject areas

  • Nephrology

Cite this

Gentamicin inhibits renal protein and phospholipid metabolism in rats : Implications involving intracellular trafficking. / Sundin, D. P.; Sandoval, R.; Molitoris, Bruce.

In: Journal of the American Society of Nephrology, Vol. 12, No. 1, 2001, p. 114-123.

Research output: Contribution to journalArticle

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