Interactions of free and liposomal amphotericin B with renal proximal tubular cells in primary culture

V Joly, L Saint-Julien, C Carbon and P Yeni

Laboratoire d'Etude des infections Experimentales, Institut National de la Sante et de le Recherche Medicale U 13, Faculte Xavier Bichat, Paris France.

We studied in vitro the renal toxicity of amphotericin B (AMB) and liposomal AMB using primary cultures of rabbit proximal tubular cells grown to confluence in serum-free medium. Toxicity was assessed by changes 1) in the Na(+)-dependent uptakes of P1 and alpha- methylglucopyranoside (MGP), characteristic functions of proximal tubular cells; 2) K+ release into the supernatant, dependent upon membrane permeability; and 3) lactic dehydrogenase release as a marker for cellular death. Cells were exposed for 1 hr to AMB, alone or intercalated in small unilamellar vesicles prepared with one of the following phospholipids: dipalmitoylphosphatidyl choline, distearoylphosphatidyl choline or dimyristoylphosphatidyl choline. Although AMB concentrations of 20 microM or less did not increase lactic dehydrogenase release, P1 and MGP uptakes were significantly reduced (50% inhibition) by 2.5 and 5 microM AMB, respectively. AMB toxicity was dose-dependent, up to 20 microM. Analysis of P1 and MGP uptake kinetics, after treatment of the cells with 10 microM AMB, showed that inhibition occurred through a decrease in Vmax (66 and 57% inhibition for P1 and MGP, respectively) without affecting Km value. K+ release appeared for 2.5 microM AMB and increased with higher concentrations. Alteration of Na(+)-dependent uptakes by AMB, which parallels K+ release, may result from an alteration of the sodium gradient. Na(+)-dependent uptakes and K+ release were unaffected by liposomal AMB, even at the highest concentration tested (80 microM). The protective effect of liposomes was the same regardless of the phospholipid used.(ABSTRACT TRUNCATED AT 250 WORDS)

Volume 255, Issue 1, pp. 17-22, 10/01/1990
Copyright © 1990 by American Society for Pharmacology and Experimental Therapeutics

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