Cardiac cell toxicity induced by 4-hydroperoxycyclophosphamide is modulated by glutathione.
OBJECTIVE
Cardiac myocytes were exposed to 4-hydroperoxycyclophosphamide (4-HC, an activated derivative of cyclophosphamide) to assess whether early ionic events are associated with the dose limiting toxicity of this chemotherapeutic agent.


METHODS
Primary cultures of embryonic chick cardiac myocytes were grown to confluency and then exposed to a medium containing 4-HC. Cellular sodium, potassium, and calcium contents were measured by atomic absorption spectrophotometry and related to protein and ATP content. Pretreatment of the cultured heart cells with glutathione depleting or enhancing agents provided the basis for evaluating the involvement of glutathione in the 4-HC-induced cytotoxicity.


RESULTS
Administration of 150 microM 4-HC to cardiac myocytes resulted in increases in cellular sodium and calcium contents and decreases in potassium, ATP, and protein contents. Pretreatment of cardiac myocytes with L-buthionine-SR-sulphoximine, a specific inhibitor of gamma-glutamylcysteine synthetase, depleted cellular glutathione to 12% of control and significantly reduced the minimum concentration of 4-HC causing cytotoxic changes. Conversely, elevation of cellular thiol content by the pretreatment of cardiac myocytes with glutathione monoethyl ester (but not glutathione) provided protection against 4-HC induced cytotoxicity.


CONCLUSIONS
Cellular glutahione concentration can markedly influence the 4-HC induced changes in cellular ion content and ATP, which are early indicators of 4-HC induced cytotoxicity.
Levine
E S
ES
Duke University Medical Center, Durham, NC 27710.
Friedman
H S
HS
Griffith
O W
OW
Colvin
O M
OM
Raynor
J H
JH
Lieberman
M
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002642:Chick Embryo; D003520:Cyclophosphamide / Q000031:analogs & derivatives* / Q000633:toxicity; D005978:Glutathione / Q000031:analogs & derivatives / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
D011506:Proteins; C042431:S-ethyl glutathione; D000255:Adenosine Triphosphate; D003520:Cyclophosphamide; D012964:Sodium; D005978:Glutathione; D011188:Potassium; D002118:Calcium; C011272:perfosfamide