Reversal of thermochemotherapeutic resistance to rhodamine 123 by verapamil

D. N. Krag, Alain P Theon, L. Gan, T. S. Shen, J. Wardell

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Rhodamine 123 (R123) cytotoxicity and intracellular accumulation were studied at elevated temperature in R123-sensitive and R123-resistant B16 mouse melanoma cell lines. Hyperthermic potentiation of R123 cytotoxicity, present in the parental R123-sensitive cell line, was not present in the R123-resistant cell line. R123-resistant melanoma cells did not develop concomitant resistance to hyperthermia. Hyperthermic potentiation of R123 cytotoxicity was restored in the resistant cells by co-treatment with verapamil. Restoration of hyperthermic potentiation of R123 by verapamil in R123-resistant cells was accompanied by increased intracellular accumulation and decreased efflux of R123. These results suggest that verapamil may be used to reestablish thermal enhancement of drug cytotoxicity when thermochemotherapeutic resistance is present.

Original languageEnglish (US)
Pages (from-to)933-941
Number of pages9
JournalInternational Journal of Hyperthermia
Issue number5
StatePublished - 1990

ASJC Scopus subject areas

  • Cancer Research
  • Physiology
  • Radiological and Ultrasound Technology
  • Physiology (medical)


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