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Measurement of polyene antibiotic-mediated erythrocyte damage by release of hemoglobin and radioactive chromium
Abstract:
Polyene antifungal antibiotics produce various degrees of membrane damage in sheep erythrocytes in vitro. Mediocidin, filipin, amphotericin B, and candicidin were found to result in greater damage than nystatin, pimaricin, and amphotericin B methyl ester. The degree of sensitivity of the cells varied by 100-fold for mediocidin verus amphotericin B methyl ester as measured by curves of hemoglobin release versus drug concentration. In erythrocytes prelabeled with radioactive chromium, release of the isotope through polyene-damaged cell membranes was found to occur at lower drug concentrations than measurable hemoglobin release, and the percentage of isotope released at the highest drug dose was consistently greater than the percentage of hemoglobin released. Thus, the isotope assay is a more sensitive indicator of polyene-induced membrane damage in the test system. These significant differences in release of molecules through polyene-induced membrane lesions indicate the complex nature of the binding and further interactions of this class of drugs with the plasma membrane.
Insights
Polyene antifungal antibiotics cause varying sheep red blood cell membrane damage. A radioactive chromium assay is more sensitive than hemoglobin release for detecting this polyene-induced membrane damage.
Area of Science:
- Pharmacology
- Biochemistry
- Cell Biology
Background:
- Polyene antifungal antibiotics are crucial for treating fungal infections.
- These drugs interact with cell membranes, leading to potential toxicity.
- Understanding their membrane interactions is vital for therapeutic development.
Purpose of the Study:
- To compare the membrane-damaging effects of various polyene antifungal antibiotics on sheep erythrocytes in vitro.
- To evaluate the sensitivity of different assays for detecting polyene-induced membrane damage.
Main Methods:
- Sheep erythrocytes were exposed to different polyene antifungal antibiotics (mediocidin, filipin, amphotericin B, candicidin, nystatin, pimaricin, amphotericin B methyl ester).
- Hemoglobin release was measured as an indicator of cell lysis.
- Erythrocytes prelabeled with radioactive chromium were used to assess membrane permeability changes.
Main Results:
- Polyene antibiotics exhibited varying degrees of erythrocyte membrane damage.
- Mediocidin, filipin, amphotericin B, and candicidin caused greater damage than nystatin, pimaricin, and amphotericin B methyl ester.
- Radioactive chromium release was a more sensitive indicator of membrane damage than hemoglobin release, occurring at lower drug concentrations.
Conclusions:
- Significant differences in the extent of membrane damage and molecule release were observed among polyene antifungal antibiotics.
- The study highlights the complex interactions between polyene drugs and the plasma membrane.
- A radioactive isotope assay offers superior sensitivity for detecting polyene-induced membrane damage compared to hemoglobin release.