Dissociation between the induction of potassium efflux and cytostatic activity of polyene macrolides in mammalian cells

Abstract

The paper contains data on the induction of K+ efflux and viability of baby hamster kidney (BHK-21) cells after their treatment with macrolide antibiotics inducing specific pores in membrane. New water-soluble semisynthetic derivatives of amphotericin B and aureofacin (N-glycosyl and trimethylammonium methyl ester derivatives) as well as the parent compounds were used to compare the concentration of antibiotics inducing permeabilizing and cytostatic effects. We found that a two-to eight-times-higher concentration of polyene antibiotic was required to observe a cytostatic effect than for release of 50% of the cellular potassium (Kr5o concentration) from BHK-21 cells. These differences were larger for water-soluble derivatives than for the parent compounds. The amount of intracellular potassium in treated cells incubated under optimal growth conditions was higher than that in cells which had been further washed with K+-free maintenance medium. The membrane permeability changes induced by low concentrations of specific polyenes were observed to be reversible. BHK-21 cells were able to repair polyene-induced membrane permeability within 3 to 12 h under optimal growth conditions, after cell treatment with K5w concentration of specific macrolide antibiotics. The repair phenomenon is postulated as an explanation for the dissociation observed between permeabilizing and cytostatic effect of specific polyenes in BHK-21 cells.

Repair of membrane alterations induced in baby hamster kidney cells by polyene macrolide antibiotics

“…This observation was supported later by other investigators using Chlorella vulgaris (2,4,17), Candida albicans (5), Histoplasma capsulatum (1), and animal cells grown in vitro (13,19 The main pharmacological utility of polyenes is based primarily on the quantitative differences in the affinity of these antibiotics for ergosterol and cholesterol in fungal (pathogen) and mammalian (host) cell membranes, respectively (11); therefore, polyene macrolide treatment affects the pathogen as well as the host. It is important to determine and find differential conditions in which host cells can recover from polyene treatment while pathogenic organisms are inhibited or killed.…”

“…This observation was supported later by other investigators using Chlorella vulgaris (2,4,17), Candida albicans (5), Histoplasma capsulatum (1), and animal cells grown in vitro (13,19). However, the nature of the repair of membrane alterations, as well as essential factors influencing this process, remains unknown.…”

Effect of lipid composition and liposome size on toxicity and in vitro fungicidal activity of liposome-intercalated amphotericin B

“…The superiority of the non-sterol-containing composition in vitro could be due to the ability of such liposomes to remove cholesterol from the cell membrane (9), thus making the cell less sensitive to the effects of amphotericin B. Whether a similar result would be observed in other in vitro toxicity tests such as K+ efflux measurements (22,23) or erythrocyte hemolysis (26) is not known. However, it is clear that the tissue culture cytotoxicity test cannot replace the in vivo assay for predicting the lethal dose response to liposomal amphotericin B.…”

“…Our results for both the deoxycholate and liposome amphotericin B agree with those of previous studies. Others have shown that, after 24 h of incubation, the growth of baby hamster kidney cells was significantly reduced by 5 ,ug and totally inhibited by 15 ,ug of amphotericin B per ml as the deoxycholate dispersion (22). For L-929 and HeLa cells, viability was decreased after a 2-h incubation with 40 p,g of Fungizone per ml as assessed by trypan blue exclusion (18).…”

“…The slower rate of transfer would lead to less damage and might permit the damage to be repaired. At low concentrations of amphotericin B, membrane damage, as assessed by potassium efflux from hamster cells, is reversible (22,23).…”