Mechanism of ischemia-enhanced aminoglycoside binding and uptake by proximal tubule cells
| Autor: | B. A. Molitoris, Alison Geerdes, Rolf Dahl, Chris Meyer |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
Male
medicine.medical_specialty Time Factors Brush border Physiology Ischemia Biology Pharmacology Phosphatidylinositols Endocytosis Nephrotoxicity Kidney Tubules Proximal Rats Sprague-Dawley chemistry.chemical_compound Internal medicine medicine Animals Phosphatidylinositol Kidney Cell Membrane Aminoglycoside medicine.disease Immunohistochemistry Rats Aminoglycosides Endocrinology medicine.anatomical_structure chemistry Type C Phospholipases Reperfusion Toxicity Gentamicins |
| Zdroj: | American Journal of Physiology-Renal Physiology. 264:F907-F916 |
| ISSN: | 1522-1466 1931-857X |
| DOI: | 10.1152/ajprenal.1993.264.5.f907 |
| Popis: | Preceding ischemia or concurrent hypotension is known to enhance aminoglycoside nephrotoxicity; however, the underlying mechanisms responsible have not been determined. To investigate the effect of preceding mild ischemia on cellular gentamicin handling, brush-border membrane vesicle binding and in vivo cellular gentamicin uptake were quantified using [3H]gentamicin as a tracer. Fifteen minutes of ischemia resulted in a marked increase in apical membrane gentamicin binding (2.8 +/- 0.4 vs. 4.9 +/- 0.8 nmol/mg protein, P < 0.01). This increase was associated with an increased number of binding sites (3.7 +/- 0.3 vs. 9.1 +/- 2.3 nmol/mg protein, P < 0.01) and a reduced binding affinity (11.8 +/- 2.2 vs. 27.7 +/- 10.4 microM, P < 0.01). This increase in gentamicin binding was accompanied by alterations in apical membrane phospholipids including a doubling of phosphatidylinositol (PI) levels (13.8 +/- 0.4 vs. 27.5 +/- 3.1 nmol/mg protein, P < 0.01). Furthermore, treatment of apical membrane vesicles with PI-specific phospholipase C markedly reduced the difference in gentamicin binding between paired control and ischemic membrane fractions. Increased gentamicin binding was associated with increased in vivo uptake of gentamicin by S1/S2 and S3 cells. Outer cortical uptake of gentamicin increased from 2.18 +/- 0.39 to 2.68 +/- 0.27 nmol/mg protein (P < 0.01) after 15 min of ischemia and 4 h of reperfusion. Juxtamedullary uptake also increased from 1.39 +/- 0.31 to 1.75 +/- 0.12 nmol/mg protein (P < 0.01). Immunocytochemical techniques, utilizing immunogold labeling, showed gentamicin was taken up via the receptor-mediated endocytic pathway by S1/S2 and S3 cells. After ischemic injury gentamicin was localized in abnormal intracellular accumulations in S3 but not S1 or S2 cells. Taken together, these data indicate ischemia results in a marked increase in apical gentamicin binding due to increases in apical PI content. This is associated with increased internalization by S1/S2 and S3 cells and abnormal intracellular compartmentalization of gentamicin within S3 cells. |
| Databáze: | OpenAIRE |
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